Spectropolarimetry of the 3.4 micron absorption feature in NGC 1068

/Langmuir©2010American Chemical SocietyIonic Liquid-Based Route to Spherical NaYF4Nanoclusters with the Assistance of Microwave Radiation and Their Multicolor UpconversionLuminescenceCheng Chen,†,‡Ling-Dong Sun,†Zhen-Xing Li,†Le-Le Li,†Jun Zhang,*,‡Ya-Wen Zhang,†and Chun-Hua Yan*,††Beijing National Laboratory for Molecular Sciences,State Key Lab of Rare Earth Materials Chemistry and Applications,PKU-HKU Joint Lab in Rare Earth Materials and Bioinorganic Chemistry,Peking University, Beijing100871,P.R.China,and‡College of Chemistry and Chemical Engineering,Inner Mongolia University,Hohhot010021,P.R.ChinaReceived December2,2009.Revised Manuscript Received January3,2010An ionic liquid(IL)(1-butyl-3-methylimidazolium tetrafluoroborate)-based route was introduced into the synthesis of novel spherical NaYF4nanoclusters with the assistance of a microwave-accelerated reaction system.X-ray diffraction (XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution TEM (HRTEM),selected area electron diffraction(SAED),energy-dispersive X-ray spectroscopy(EDS)and upconversion (UC)luminescence spectroscopy were used to characterize the obtained products.Interestingly,these spherical NaYF4 nanoclusters with diameters ranging from200to430nm are formed by the self-assembly of small nanoparticles.The diameters of the nanoclusters could be easily tuned just by changing the amounts of the precursors.By conducting the control experiments with different ILs or precursors,it is proven that the ILs have played key roles,such as the solvents for the reaction,the absorbents of microwave irradiation,and the major fluorine sources for the formation of the NaYF4 nanocrystals.The UC luminescence properties of the Ln3þcodoped NaYF4were measured,and the results indicate that the nanoclusters obtained in BmimBF4exhibit excellent UC properties.Since this IL-based and microwave-accelerated procedure is efficient and environmentally benign,we believe that this method may have some potential applications in the synthesis of other nanomaterials.1.IntroductionIonic liquids(ILs)have recently attracted much attention since they have a variety of potential applications in organic synthesis, electrochemistry,catalysis,chemical separation,and so on.1ILs can be used as green solvents to replace conventional organic solvents in many chemical processes because of their unique properties,such as their negligible vapor pressure,good thermal and chemical stability,extremely high ionic conductivity,wide electrochemical windows,and so on.2,3In recent years,ILs have emerged as one of the most promising categories of medium for the fabrication of nanomaterials with various morphologies,since ILs possess tunable properties so that they can easily interact with various surfaces and chemical reaction environments.4-6 Smarsly et al.designed a low-temperature route to synthesize rutile nanorods just by the stabilization of an amorphous phase,which then converted to rutile by a simple extraction of the stabilizer (IL).7Chen et al.demonstrated a novel route for the prepara-tion of IL-stabilized ZnO nanocrystals with remarkably high photoluminescence quantum yields.8Moreover,because of their high polarity,ILs are also considered to be excellent microwave absorbents.9Microwave dielectric heating has aroused many interests in recent years because there are many advantages compared to conventional heating for chemical reactions,such as higher heating rate,uniform heating without thermal gradients, selective heating properties,and higher yields in shorter reaction time.10,11Because of these special properties,microwave irradia-tion is becoming an important pathway for the preparation of nanomaterials.It not only benefits the spontaneous nucleation of inorganic materials,12-14but also enables reactions to be per-formed at higher temperatures,which results from the super-heating phenomenon of the solvents caused by the microwave dielectric heating.15,16The exploration of the combination be-tween ILs and microwave radiation has just begun,which would facilitate the fabrication of novel nanomaterials with designed structures and functions.17-19*Corresponding author.Fax:þ86-10-6275-4179;e-mail:yan@(C.-H.Y.).Fax:þ86-471-499-2278;e-mail:cejzhang@(J.Z.).(1)Parvulescu,V.I.;Hardacre,C.Chem.Rev.2007,107,2615.(2)Antonietti,M.;Kuang,D.B.;Smarsly,B.;Zhou,Y.Angew.Chem.,Int.Ed. 2004,43,4988.(3)Gao,H.X.;Li,J.C.;Han,B.X.;Chen,W.N.;Zhang,J.L.;Zhang,R.;Yan,D.D.Phys.Chem.Chem.Phys.2004,6,2914.(4)Lodge,T.P.Science2008,321,50.(5)Kim,T.Y.;Kim,W.J.;Hong,S.H.;Kim,J.E.;Suh,K.S.Angew.Chem., Int.Ed.2009,48,3806.(6)Zhou,Y.;Antonietti,M.Adv.Mater.2003,15,1452.(7)Kaper,H.;Endres,F.;Djerdj,I.;Antonietti,M.;Smarsly,B.M.;Maier,J.; Hu,Y.S.Small2007,3,1753.(8)Liu,D.P.;Li,G.D.;Su,Y.;Chen,J.S.Angew.Chem.,Int.Ed.2006,45, 7370.(9)Ding,K.L.;Miao,Z.J.;Liu,Z.M.;Zhang,Z.F.;Han,B.X.;An,G.M.; Miao,S.D.;Xie,Y.J.Am.Chem.Soc.2007,129,6362.(10)Gabriel,C.;Gabriel,S.;Grant,E.H.;Halstead,B.S.J.;Mingos,D.M.P. Chem.Soc.Rev.1998,27,213.(11)Hu,X.L.;Yu,J.C.Adv.Funct.Mater.2008,18,880.(12)Gerbec,J.A.;Magana,D.;Washington,A.;Strouse,G.F.J.Am.Chem. Soc.2005,127,15791.(13)Kim,S.H.;Lee,S.Y.;Yi,G.R.;Pine,D.J.;Yang,S.M.J.Am.Chem.Soc. 2006,128,10897.(14)Hu,X.L.;Gong,J.M.;Zhang,L.Z.;Yu,J.C.Adv.Mater.2008,20,4845.(15)Baghurst,D.R.;Mingos,mun.1992,9, 674.(16)Saillard,R.;Poux,M.;Berlan,J.Tetrahedron1995,51,4033.(17)Yang,L.X.;Zhu,Y.J.;Wang,W.W.;Tong,H.;Ruan,M.L.J.Phys. Chem.B2006,110,6609.(18)Buhler,G.;Feldmann,C.Angew.Chem.,Int.Ed.2006,45,4864.(19)Lovingood,D.D.;Strouse,G.F.Nano.Lett.2008,8,3394.Article Chen et al.Recent decades have witnessed an explosion in research devoted to preparing upconversion(UC)nanocrystals because of their potential applications in solid-state lasers,optical sto-rage,flat-panel displays,optical fiber-based telecommunica-tions,low-intensity IR imaging,and so on.20,21As an impor-tant category of rare earth fluoride compounds,AREF4(A= alkali;RE=rare earth)is regarded as an excellent host matrix for UC phosphors.22,23Great efforts have been devoted to the synthesis of shape-controllable NaYF4nanocrystals via different routes and the study of their optical properties.24-26Zhao et al. reported the synthesis of NaYF4nanotubes via an in situ ion exchange procedure from the corresponding hydroxides.27van Veggel’s group developed an efficient route to prepare a UC nanoparticle-polymer composite.28A core/shell structure of NaYF4/silica was prepared by Zhang’s group,and multi-color UC fluorescence properties of the nanoparticles were measured.29,30Recently,IL was also applied to synthesize hexagonal-phase NaYF4UC nanophosphors through an ionothermal method.31However,the unique properties of ILs, such as their high polarity and the resulting excellent microwave absorbing ability,have not been reflected and emphasized. Additionally,the effects of different ILs on the formation process of the final nanostructures have not been investigated.In this work,we have introduced a microwave-accelerated reaction system into the synthesis of novel spherical NaYF4 nanoclusters in1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4),with which the reactions could be completed in a significantly short time and highly crystallized products could be obtained.Interestingly,these NaYF4nanoclusters are formed by the self-assembly of small nanoparticles and exhibit excellent UC luminescent property.By conducting control experiments,it is proven that ILs play key roles in the formation of the final nanostructure,since they act not only as the solvents and micro-wave absorbents in the synthetic process,but also as the major fluorine sources for the preparation of NaYF4nanocrystals.2.Experimental Section2.1.Materials.Trifluoroacetic acid(99%,Acros),Na-(CF3COO)(>97%,Acros),Na(CH3COO)(99.0%,Beijing Che-mical Plant),1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4,99%,Alpha),1-butyl-3-methylimidazolium hexa-fluorophosphate(BmimPF6,98%,Alpha),and1-butyl-3-methyl-imidazolium bromide(BmimBr,99%,Alpha)were used as received.RE(CF3COO)3(RE=Y,Yb,Er,Tm)and Y(CH3COO)3 were prepared from the corresponding lanthanide oxides follow-ing the literature method.322.2.Synthesis of NaYF4with Trifluoroacetate Salts in BmimBF4.For a typical synthesis,0.5mmol Na(CF3COO)and0.5mmol Y(CF3COO)3were taken as the precursors and added into5mL IL(BmimBF4)followed by vigorously magnetic stirring at room temperature for2h to obtain a transparent solution,which was then heated to200°C by microwave irradiation and maintained for5min.The temperature ramping process was accomplished by two steps(20°C/min from room temperature to100°C and then10°C/min from100to200°C)in a CEM microwave-accelerated system at400W.After the microwave reaction was completed,the temperature of the system was reduced to room temperature.Then after washing and centrifugation several times,white precipitates were collected and dried at65°C.2.3.Synthesis of NaYF4with Acetate Salts in BmimBF4. The synthetic procedure was the same as that used to synthesize cubic NaYF4in BmimBF4,except that0.5mmol Na(CH3COO) and0.5mmol Y(CH3COO)3were taken as the precursors instead of the trifluoroacetate salts.2.4.Reaction of Trifluoroacetate Salts in BmimBr.The synthetic procedure was the same as that used to synthesize cubic NaYF4by the reaction of Na(CF3COO)and Y(CF3COO)3, except that BmimBr was used as the solvent instead of BmimBF4.2.5.Synthesis of NaYF4with Trifluoroacetate Salts in BmimPF6.The synthetic procedure was the same as that used to synthesize cubic NaYF4by the reaction of Na(CF3COO)and Y(CF3COO)3,except that BmimPF6was used as the solvent instead of BmimBF4.2.6.Synthesis of NaYF4:Yb,Er and NaYF4:Yb,Tm with Trifluoroacetate Salts in BmimBF4.The synthetic procedure was the same as that used to synthesize cubic NaYF4in BmimBF4, except that0.5mmol Na(CF3COO)and stoichiometric amounts of Y(CF3COO)3,Yb(CF3COO)3,Er(CF3COO)3/Tm(CF3COO)3 were taken as the precursors.2.7.Synthesis of NaYF4:Yb,Er and NaYF4:Yb,Tm with Trifluoroacetate Salts in BmimPF6.The synthetic procedure was the same as that used to synthesize cubic NaYF4in BmimPF6, except that0.5mmol Na(CF3COO)and stoichiometric amounts of Y(CF3COO)3,Yb(CF3COO)3,Er(CF3COO)3/Tm(CF3COO)3 were taken as the precursors.2.8.Characterization.Powder X-ray diffraction(XRD) patterns of the dried powders were recorded on a Rigaku D/ MAX-2000diffractometer(Japan)with Cu K R radiation(λ= 1.5406A).Scanning electron microscopy(SEM)observations were carried out with DB-235focused ion beam(FIB)system operated at an acceleration voltage of15kV.Transmission electronic microscopy(TEM),and selected area electron diffrac-tion(SAED)were performed with a JEOL-2100transmission electron microscope(Japan)operated at200kV.High-resolution TEM(HRTEM)characterization and energy-dispersive X-ray spectroscopy(EDS)were taken on a JEOL-2100F transmission electron microscope(Japan)equipped with an EDS detector.The UC luminescence spectra were recorded on a Hitachi F-4500 fluorescence spectrophotometer equipped with an external tun-able2W980nm laser diode(P max=500mW at1000mA).3.Results and DiscussionThe combination of ILs and microwave dielectric heating could provide us with a facile and green route to fabricate nanomater-ials.The XRD pattern of the product synthesized with trifluor-oacetate salts(Na(CF3COO)and Y(CF3COO)3)in BmimBF4is shown in Figure1a.All the peaks can be well indexed as a cubic phase of NaYF4(JCPDS card No.39-0724).The well-resolved four peaks between20°and60°in2θvalue could be assigned to (111),(200),(220),and(311)planes of cubic NaYF4nanocrystals. The SEM image(Figure2a)indicates that NaYF4nanospheres with diameters ranging from200to430nm could be obtained. The TEM image(Figure2b)shows that these spherical nanoclus-ters have rough surfaces,and they are formed by the self-assembly of small nanoparticles.The inset of Figure2b is the SAED pattern(20)Zhang,F.;Wan,Y.;Yu,T.;Zhang,F.Q.;Shi,Y.F.;Xie,S.H.;Li,Y.G.; Xu,L.;Tu,B.;Zhao,D.Y.Angew.Chem.,Int.Ed.2007,46,7976.(21)Sivakumar,S.;van Veggel,F.C.J.M.;May,P.S.J.Am.Chem.Soc.2007, 129,620.(22)Boyer,J.C.;Cuccia,L.A.;Capobianco,J.A.Nano.Lett.2007,7,847.(23)Li,C.X.;Yang,J.;Yang,P.P.;Zhang,X.M.;Lian,H.Z.;Lin,J.Cryst. Growth Des.2008,8,923.(24)Mai,H.X.;Zhang,Y.W.;Si,R.;Yan,Z.G.;Sun,L.D.;You,L.P.;Yan,C.H.J.Am.Chem.Soc.2007,129,6362.(25)Wang,L.Y.;Li,Y.D.Chem.Mater.2007,19,727.(26)Wang,H.Q.;Nann,T.ACS Nano2009,3,3804.(27)Zhang,F.;Zhao,D.Y.ACS Nano2009,3,159.(28)Boyer,J.C.;Johnson,N.J.J.;van Veggel,F.C.J.M.Chem.Mater.2009, 21,2010.(29)Li,Z.Q.;Zhang,Y.;Jiang,S.Adv.Mater.2008,20,4765.(30)Qian,H.S.;Guo,H.C.;Ho,P.C.L.;Mahendran,R.;Zhang,Y.Small 2009,5,2285.(31)Liu,X.M.;Zhao,J.W.;Sun,Y.J.;Song,K.;Yu,Y.;Du,C.;Kong,X.G.; Zhang,mun.2009,43,6628.(32)Roberts,J.E.J.Am.Chem.Soc.1961,83,1087.Chen et al.Articletaken on a single sphere.The discontinuous rings again reveal that the cluster is formed by the aggregation of many small nanopar-ticles.Observation from the HRTEM image (Figure 2c)reveals that the size of the small nanoparticles in these nanoclusters is about 10to 15nm.Moreover,the nanoparticles are single crystals with an interplanar spacing of 0.31nm corresponding to the (111)facets of cubic NaYF 4,which confirms that the nanoparticles are highly crystallized.Scheme 1illustrates the formation process of the spherical NaYF 4nanoclusters.Since the ILs with high polarity have strong microwave absorbing ability,the whole reaction system could reach a high temperature rapidly under microwave irradiation,which results in spontaneous nucleation.9Followed by the rapid growth of these nuclei,large quantities of NaYF 4nanocrystals are formed within an extremely short time.Therefore,the size of the as-synthesized nanoparticles is very small.Because of their high surface energy,the freshly formed small nanoparticles tend to aggregate rapidly into spherical nanoclusters.14Furthermore,the size of the spherical NaYF 4nanoclusters could be tuned by changing the amounts of the trifluoroacetate precursors.As shown in Table 1,samples 1-3were prepared bychanging the amounts of the trifluoroacetate salts from 0.5to 0.1mmol.It could be observed from the TEM images in Figure 3a,c,e that the size of the NaYF 4nanoclusters decreases with the decrease of the precursors’amounts.By measuring 200nanoclusters for each sample,we could get the size distribu-tions of the nanoclusters (Figure 3b,d,f),and the average sizes of these three samples are 302,163,and 79nm,respectively.This size tunability could be resulted from the differences in crystal nuclei caused by varying additions of the precursors.33Because higher concentration of trifluoroacetate salts could accelerate the decom-position of Na(CF 3COO)and Y(CF 3COO)3,more nuclei would form in the solution,which leads to the formation of larger NaYF 4nanoclusters.The factors governing the formation of the spherical NaYF 4nanoclusters were studied,and it was found that the IL had played key roles in the self-assembly process of the final nano-structure.As is known,the existence of sodium,yttrium,and fluorine sources is indispensable for the formation of NaYF 4nanocrystals.In this method,both the precursors (trifluoroace-tate salts)and the solvent (BmimBF 4)might serve as the supplier of the fluoride ions.In order to investigate where the fluoride ions came from and the role that IL played on the synthetic procedure of NaYF 4,control experiments were carried out by changing the inorganic precursors or the ILs while keeping other synthetic parameters constant.Figure 1c shows the XRD pattern of the sample obtained by the reaction of acetate salts Na(CH 3COO)and Y(CH 3COO)3in BmimBF 4.It can be clearly observed that cubic NaYF 4could also be obtained without the existence of CF 3COO -.This indicates that the IL provided the fluorine source for the formation of NaYF 4by the decomposition of BmimBF 4,which compares well with the reported results that BF 4-ions are prone to thermal decomposition to produce F -at a certain temperature.34,35To further confirm it,another control experi-ment was carried out just by changing the molecular composition of the ILs.The XRD pattern (Figure 1d)shows that NaYF 4couldFigure 1.(a)XRD pattern of NaYF 4synthesized via the reaction of trifluoroacetate precursors in BmimBF 4.(b)XRD pattern of NaYF 4synthesized via the reaction of trifluoroacetate precursors in BmimPF 6.(c)XRD pattern of NaYF 4synthesized via the reaction of acetate precursors in BmimBF 4.(d)XRD pattern of the product synthesized via the reaction of trifluoroacetate pre-cursors inBmimBr.Figure 2.(a)SEM image of the NaYF 4nanoclusters obtained inBmimBF 4.(b)TEM image of two NaYF 4nanoclusters obtained in BmimBF 4and the ED pattern (inset).(c)HRTEM image taken on the edge of a NaYF 4nanocluster.Scheme 1.Schematic Representation of the Formation of NaYF 4Nanocrystals Obtained in DifferentILsTable 1.Average Diameters of the NaYF 4Nanoclusters Obtained via the Reaction of Different Amounts of Trifluoroacetate Precursorsin BmimBF 4sampleNa(CF 3COO)/mmolY(CF 3COO)3/mmolaverage diameters/nm 10.50.530220.250.2516330.10.179(33)Ge,J.P.;Hu,Y.X.;Biasini,M.;Beyermann,W.P.;Yin,Y.D.Angew.Chem.,Int.Ed.2007,46,4342.(34)Fox,D.;Gilman,J.;Long,H.D.;Trulove,P.J.Chem.Thermodyn.2005,37,900.(35)Koval’chuk, E.;Reshetnyak,O.;Kozlovs’ka,Z.;B z a’ejowski,J.;Gladyshevs’kyj,R.;Obushak,M.Thermochim.Acta 2006,444,1.Article Chen et al.not be synthesized under the same condition by the use of trifluoroacetate salts (Na(CF 3COO)and Y(CF 3COO)3)and IL bearing bromide (BmimBr),and no signal of fluorine was detected by EDS for the final product (Figure 4a,b),which also pointed out that CF 3COO -did not decompose during the micro-wave heating process and did not provide the indispensable F -for the preparation of NaYF 4.The results of the above experiments illuminated that BmimBF 4not only served as the solvent and microwave absorbent in the whole synthetic process,but also acted as the building block and the major fluorine source for the formation of NaYF 4nanoclusters.Based on the above analysis,it is reasonable to deduce that NaYF 4nanocrystals may also be synthesized in other ILs bearing fluorine.So we applied the same synthetic procedure to prepare NaYF 4nanocrystals in BmimPF 6.As we expected,the XRD pattern (Figure 1b)shows that cubic NaYF 4could be achieved,but a peak of NaF was observed at 38.4°in 2θvalue.This probably could be explained as follows:The thermal degradation of BmimPF 6is relatively easier than that of BmimBF 4,36because the bond energy of P -F is weaker compared with that of B -F.19Therefore,high concentration of fluoride ions could be presented in the system of BmimPF 6,which might lead to the formation of NaF.The TEM image in Figure 5a illustrates that spherical to ellipsoidal nanoparticles could be obtained in BmimPF 6.The interplanar spacing shown in the HRTEM image (Figure 5b)is about 0.31nm corresponding to the (111)facets of cubic NaYF 4,which confirms that the nanoparticles are single crystals with high crystallinity.By comparison of Figure 2b and Figure 5a,we caneasily see that the morphology of the NaYF 4nanocrystals obtained in BmimPF 6is different from that of the nanoclusters obtained in BmimBF 4.This may be caused by the different viscosities of these two ILs.As is reported by Afonso´s group,the viscosity of BmimPF 6is higher than that of BmimBF 4.37Thus the assembly and aggregation of the small nanoparticles might be prevented to some extent in BmimPF 6,thus affecting the final morphology.In order to elucidate the effect of microwave dielectric heating on the preparation of the NaYF 4nanoclusters,the comparison between the samples synthesized through the ionothermal method and the microwave method was investigated.The XRD pattern (Figure S1in the Supporting Information)indicates that the product of the ionothermal treatment is cubic NaYF 4.TEM images (Figure S2in the Supporting Information)show that the aggregates of NaYF 4nanoparticles could also be obtained.However,the shape of these aggregates is not as regular as the spherical nanoclusters obtained through the microwave method.At the same time,some rectangular structures could also be observed in the same sample.The existence of different structures in the product may have resulted from the thermal gradients in the ionothermal reaction system.The vessel for the ionothermal reaction serves as an intermediary in the whole process,through which the energy could transfer from the oven to the solvent and then to the reactants.This could result in thermal gradients throughout the bulk solution,which lead to the formation of nonuniform reaction conditions.12However,the effect of thermal gradients could be eliminated in the microwave-accelerated system,which leads to the uniform morphology of the NaYF 4nanocrystals.The UC emission can be realized by doping cubic NaYF 4with lanthanide ions.The morphologies of the UC nanocrystals are not affected by doping with Ln 3þ(Figure 6).Figure 7a,b shows the fluorescence spectra for a 1wt %colloidal solution of NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,0.2%Tm 3þin these two different ILs (BmimBF 4and BmimPF 6)under the excitation of a 980nm laser diode.The spectra of NaYF 4:Yb 3þ,Er 3þnanocrystals exhibit two emission bands,which could be attributed to 2H 11/2f 4I 15/2,4S 3/2f 4I 15/2,and 4F 9/2f 4I 15/2transi-tions of Er 3þ.The emission bands of NaYF 4:Yb 3þ,Tm 3þnano-crystals at 450-500nm and 630-670nm could be assigned to the 1G 4f 3H 6and 1G 4f 3F 4transition of Tm 3þ.38Interestingly,the UC emission intensity of nanoclusters obtained in BmimBF 4was enhanced nearly eight times compared with that of the nanopar-ticles in BmimPF 6.It is well-known that the UC intensity may be influenced by the surface state of nanoparticles.As the ratio of the surface defects decreases,the nonradiative decay is reduced,which would cause the increase of the emission intensity.39In our work,the formation of the NaYF 4nanoclusters might result in the surface reduction of the primary nanoparticles,which is caused by the hard connection among the nanoparticles formed during the self-assembling process.Therefore,the nonradiative centers existing on the surface of the nanocrystals will be eliminated partially,which finally enhances the intensity of the NaYF 4nanoclusters.40,41Figure 7c shows the strong UC lumi-nescence photographs for the 1wt %colloidal solution of the NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,0.2%Tm 3þFigure 3.TEM images and corresponding size distributions of samples 1(a,b),2(c,d),and 3(e,f).(36)Huddleston,J.G.;Visser,A.E.;Reichert,W.M.;Willauer,H.D.;Broker,G.A.;Rogers,R.D.Green Chem.2001,3,156.(37)Branco,L.C.;Rosa,J.N.;Ramos,J.J.M.;Afonso,C.A.M.Chem.;Eur.J.2002,8,3671.(38)Wang,F.;Liu,X.G.J.Am.Chem.Soc.2008,130,5642.(39)Vetrone,F.;Naccache,R.;Mahalingam,V.;Morgan,C.G.;Capobianco,J.A.Adv.Funct.Mater.2009,19,2924.(40)Bovero,E.;van Veggel,F.C.J.M.J.Phys.Chem.C 2007,111,4529.(41)Mai,H.X.;Zhang,Y.W.;Sun,L.D.;Yan,C.H.J.Phys.Chem.C 2007,111,13721.Chen et al.Articlenanoclusters in BmimBF 4,implying that these nanoclusters are excellent UC hosts.The emission intensity of UC nanomaterials could be easily tuned just by changing the doping amounts of the lanthanide ions (Figure 8).For the NaYF 4:Yb 3þ,Er 3þnanoclus-ters obtained in BmimBF 4,the UC emission intensity obviously decreases when the concentration of Er 3þincreases from 0.2%to 2%with the Yb 3þconcentration fixed at 20%.For the NaYF 4:Yb 3þ,Tm 3þnanoclusters obtained in BmimBF 4,the UC emis-sion intensity also decreases with the increase of the Tm 3þconcentration from 0.2%to 2%,while keeping the concentration of Yb 3þat 20%.According to these results,it could be concluded that higher concentrations of Er 3þor Tm 3þmay cause concen-tration quenching of the spherical UC nanoclusters.41Further-more,we investigated how the size distribution affected the UC properties of the spherical NaYF 4:Yb 3þ,Er 3þ/Tm 3þnanoclus-ters.As shown in Figure 9,the UC emission intensity of NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,2%Tm 3þde-creased when the average size of the nanoclusters was reducedfrom 302to 79nm.Because of the higher surface area of the smaller nanoclusters,14the nonradiative centers existing on the surface of the nanoparticles increased with the decrease of the size of the nanoclusters.Therefore,the UC emission intensity of the large nanoclusters would be enhanced compared with that of the small nanoclusters.The influence of different thermal treatment methods (microwave irradiation and ionothermal)on the UC prop-erties of the NaYF 4:20%Yb 3þ,2%Er 3þand NaYF 4:20%Yb 3þ,2%Tm 3þnanocrystals was also studied.The results (Figure S3in the Supporting Information)illuminated that the emission intensity of the UC nanocrystals synthe-sized via the microwave dielectric heating was slightly increased compared with that of the nanocrystals synthe-sized via the ionothermal method.The reason isthatFigure 4.(a)TEM image and (b)corresponding EDS spectrum of the product obtained inBmimBr.Figure 5.(a)TEM image,(b)HRTEM image,and (c)size dis-tribution of NaYF 4nanoparticles obtained in BmimPF 6.Figure 6.TEM images of (a)R -NaYF 4:20%Yb 3þ,2%Er 3þand(b)R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoclusters obtained in BmimBF 4.TEM images of (c)R -NaYF 4:20%Yb 3þ,2%Er 3þand (d)R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoparticles obtained in BmimPF 6.Article Chen et al.relative higher crystallinity and uniformity of the nano-clusters could be achieved through the microwave irradia-tion,which resulted in the increase of the UC emission intensity.26,294.ConclusionIn summary,we have developed a rapid microwave-assisted process to synthesize cubic NaYF 4in fluorine-contained ILs.It shows that small nanoparticles could form spontaneously in BmimBF 4due to the microwave irradiation,and then spherical cubic NaYF 4nanoclusters could be obtained by the self-assembly of these primary nanoparticles.From the control experiments with different precursors or ILs,it can be concluded that ILs play key roles,such as the solvent for the reaction,the absorbent of microwave irradiation,and the source of fluoride ions for the formation of NaYF 4nanocrystals.By the investigation ofdifferent thermal treatment methods,it is also found that higher crystallinity and uniformity of the nanocrystals could be achieved in the microwave-accelerated system.The various experimental results of the UC properties indicate that the NaYF 4:Yb 3þ,Er 3þand NaYF 4:Yb 3þ,Tm 3þnanoclusters synthesized in BmimBF 4exhibit excellent luminescent properties.Therefore,the rare earth fluoride nanoclusters are expected to be applied in solid-state laser,three-dimensional flat-panel displays,light emitting diodes,and some other optics devices.Since this IL-based and micro-wave-accelerated procedure is efficient and environmentally be-nign,it may have some potential applications in the synthesis of other nanomaterials.Acknowledgment.Grants-in-aid from NSFC (20821091,20961005,and 20971005)and MOST of China (2006CB601104)are gratefullyacknowledged.Figure 7.(a)UC luminescence spectra of R -NaYF 4:20%Yb 3þ,2%Er 3þnanoclusters in BmimBF 4and R -NaYF 4:20%Yb 3þ,2%Er 3þnanoparticles in BmimPF 6.(b)UC luminescence spectra of R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoclusters in BmimBF 4and R -NaYF 4:20%Yb 3þ,0.2%Tm 3þnanoparticles in BmimPF 6.(c)UC luminescence photographs for 1wt %colloidal solution of R -NaYF 4:20%Yb 3þ,2%Er 3þ(left)and R -NaYF 4:20%Yb 3þ,0.2%Tm 3þ(right)nanoclusters in BmimBF 4.Figure 8.(a)UC luminescence spectra of R -NaYF 4:Yb 3þ,Er 3þnanoclusters with different doping concentrations of Er 3þ.(b)UCluminescence spectra of R -NaYF 4:Yb 3þ,Tm 3þnanoclusters with different doping concentrations of Tm 3þ.Figure 9.(a)UC luminescence spectra of R -NaYF 4:20%Yb 3þ,2%Er 3þnanoclusters with different average diameters.(b)UC luminescencespectra of R -NaYF 4:20%Yb 3þ,2%Tm 3þnanoclusters with different average diameters.。

秦志伟，叶博，刘玲. 采用QuEChERS 结合UHPLC-MS/MS 定量分析热加工肉制品中的三种胺类物质[J]. 食品工业科技，2022，43（19）：340−348. doi: 10.13386/j.issn1002-0306.2021120176QIN Zhiwei, YE Bo, LIU Ling. Quantitative Analysis of Three Amines in Thermally Processed Meat Products Using QuEChERS Combined with UHPLC-MS/MS[J]. Science and Technology of Food Industry, 2022, 43(19): 340−348. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2021120176· 分析检测 ·采用QuEChERS 结合UHPLC-MS/MS 定量分析热加工肉制品中的三种胺类物质秦志伟1，叶　博1,2，刘　玲1,*（1.沈阳农业大学食品学院，辽宁沈阳 110000；2.辽宁现代农业工程中心，辽宁沈阳 110000）摘　要：本文采用QuEChERS 技术结合超高效液相色谱-串联质谱（UHPLC-MS/MS ）技术建立同时检测丙烯酰胺（AA ）、亚硝胺（NAs ）和杂环胺（HAAs ）含量的方法，用于分析热加工肉制品中产生的胺类物质。

结果表明：该方法检测出的三类成分20种胺类物质在相应浓度范围内显示出良好的线性关系（R 2>0.991），检测限和定量限分别为0.01~1.6 ng/g 和0.03~4.8 ng/g ，日内回收率介于66.3%~116.5%之间，日内精密度介于0.78%~9.0%之间。

每个胺类物的5×LOQ 加标水平计算的日间精度范围为3.4%~9.4%。

惠森，朱旭浩，刘小玲，等. 牡蛎源肽锌纳米粒体外胃肠道消化稳定性及作用机制[J]. 食品工业科技，2023，44（11）：38−44. doi:10.13386/j.issn1002-0306.2022110206HUI Sen, ZHU Xuhao, LIU Xiaoling, et al. Stability and Mechanism of Oyster Peptide Hydrolysate Zinc Nanoparticles during in Vitro Gastrointestinal Digestion[J]. Science and Technology of Food Industry, 2023, 44(11): 38−44. (in Chinese with English abstract). doi:10.13386/j.issn1002-0306.2022110206· 青年编委专栏—食品营养素包埋与递送（客座主编：黄强、蔡杰、陈帅） ·牡蛎源肽锌纳米粒体外胃肠道消化稳定性及作用机制惠　森1，朱旭浩1，刘小玲1，张自然2,*（1.广西大学轻工与食品工程学院，广西南宁 530000；2.北部湾大学食品工程学院，广西钦州 535011）摘　要：本研究旨在探究体外模拟消化对牡蛎源肽锌纳米粒（OPH-Zn ）稳定性及其结构的影响，揭示OPH-Zn 在胃肠道消化过程中的动态变化规律。

采用各种光谱仪（紫外、红外和荧光）、电镜（扫描和透射）以及粒度仪测定模拟消化液中OPH-Zn 的锌含量、表面形貌、二级结构以及粒径分布变化。

研究发现，OPH-Zn 总锌含量高达228.89±2.53 mg/g ；在模拟胃液消化过程中，OPH-Zn 和ZnSO 4对照中可溶性锌含量变化不大，且两个样品无显著差异（P >0.05）；转为模拟肠液消化时，OPH-Zn 和ZnSO 4的锌溶解性分别降低了28.07%和55.31%（P <0.05），与ZnSO 4相比，OPH-Zn 可溶性锌含量显著高于ZnSO 4（P <0.05）；光谱分析发现，OPH-Zn 在模拟胃液和肠液中保持相对稳定，但在由胃液过渡到肠液时，Zn 2+与肽键中氧原子和氮原子的配位作用发生变化，电镜结果显示不同消化程度的OPH-Zn 表面微观结构和颗粒大小也存在一定差异。

Surface Enhanced Raman Spectroscopy(SERS) is a powerful analytical technique that has become increasingly popular in recent years. It is a surface-sensitive technique that allows the detection and identification of molecules with high sensitivity and specificity. In this article, we will discuss the principles and applications of SERS.Principles of SERSSERS is based on the Raman effect, which is the inelastic scattering of light by molecules. Raman scattering causes a shift in wavelength of the incident light, which can be used to identify the molecules present in a sample. However, the Raman effect is weak, and the signal from a single molecule is often too small to detect. Thus, in order to enhance the Raman signal, SERS relies on the interaction between the analyte molecules and a metallic surface.The enhancement of the Raman signal is due to the interaction between the analyte molecules and the surface plasmons of the metal. Surface plasmons are collective oscillations of electrons on the surface of the metal, which can cause a large increase in the local electromagnetic (EM) field. This enhanced EM field interacts with the analyte molecules, increasing their Raman signal by several orders of magnitude.Applications of SERSSERS has a wide range of applications, including bioanalysis, environmental monitoring, food safety, and forensic science. In bioanalysis, SERS can be used for the detection of DNA, proteins, and drugs. SERS is also used for the analysis of small molecules in biological fluids, such as glucose, cholesterol, and uric acid.In environmental monitoring, SERS can be used for the detection of pollutants and contaminants in water and soil. SERS can also be used for the identification of microorganisms, such as bacteria and viruses. In food safety, SERS is used for the detection of pesticides, toxins, and adulterants in food products.In forensic science, SERS can be used for the analysis of trace evidence, such as fibers, hair, and fingerprints. SERS can also be used for the detection of drugs in biological fluids and for the identification of explosives and other chemical compounds.Advantages and Limitations of SERSThe advantages of SERS include its high sensitivity and specificity, its ability to detect multiple analytes simultaneously, and its applicability to a wide range of samples. SERS can also be used for in situ analysis, allowing real-time monitoring of chemical reactions and biological processes.However, SERS has some limitations that should be considered when using the technique. SERS is affected by variations in the metal substrate and the analyte molecule, which can cause variability in the signal intensity. SERS is also affected by surface contamination, which can interfere with the signal from the analyte molecules.Conclusionis a powerful analytical technique that has found applications in a variety of fields, from bioanalysis to forensic science. SERS relies on the interaction between the analyte molecules and a metallic surface, which enhances the Raman signal and allows for the detection and identification of molecules with high sensitivity and specificity. While SERS has some limitations, its advantages make it a valuable tool for chemical and biological analysis.。

华中师范大学物理学院物理学专业英语仅供内部学习参考！2014一、课程的任务和教学目的通过学习《物理学专业英语》，学生将掌握物理学领域使用频率较高的专业词汇和表达方法，进而具备基本的阅读理解物理学专业文献的能力。

通过分析《物理学专业英语》课程教材中的范文，学生还将从英语角度理解物理学中个学科的研究内容和主要思想，提高学生的专业英语能力和了解物理学研究前沿的能力。

培养专业英语阅读能力，了解科技英语的特点，提高专业外语的阅读质量和阅读速度；掌握一定量的本专业英文词汇，基本达到能够独立完成一般性本专业外文资料的阅读；达到一定的笔译水平。

要求译文通顺、准确和专业化。

要求译文通顺、准确和专业化。

二、课程内容课程内容包括以下章节：物理学、经典力学、热力学、电磁学、光学、原子物理、统计力学、量子力学和狭义相对论三、基本要求1.充分利用课内时间保证充足的阅读量（约1200~1500词/学时），要求正确理解原文。

2.泛读适量课外相关英文读物，要求基本理解原文主要内容。

3.掌握基本专业词汇（不少于200词）。

4.应具有流利阅读、翻译及赏析专业英语文献，并能简单地进行写作的能力。

四、参考书目录1 Physics 物理学 (1)Introduction to physics (1)Classical and modern physics (2)Research fields (4)V ocabulary (7)2 Classical mechanics 经典力学 (10)Introduction (10)Description of classical mechanics (10)Momentum and collisions (14)Angular momentum (15)V ocabulary (16)3 Thermodynamics 热力学 (18)Introduction (18)Laws of thermodynamics (21)System models (22)Thermodynamic processes (27)Scope of thermodynamics (29)V ocabulary (30)4 Electromagnetism 电磁学 (33)Introduction (33)Electrostatics (33)Magnetostatics (35)Electromagnetic induction (40)V ocabulary (43)5 Optics 光学 (45)Introduction (45)Geometrical optics (45)Physical optics (47)Polarization (50)V ocabulary (51)6 Atomic physics 原子物理 (52)Introduction (52)Electronic configuration (52)Excitation and ionization (56)V ocabulary (59)7 Statistical mechanics 统计力学 (60)Overview (60)Fundamentals (60)Statistical ensembles (63)V ocabulary (65)8 Quantum mechanics 量子力学 (67)Introduction (67)Mathematical formulations (68)Quantization (71)Wave-particle duality (72)Quantum entanglement (75)V ocabulary (77)9 Special relativity 狭义相对论 (79)Introduction (79)Relativity of simultaneity (80)Lorentz transformations (80)Time dilation and length contraction (81)Mass-energy equivalence (82)Relativistic energy-momentum relation (86)V ocabulary (89)正文标记说明：蓝色Arial字体（例如energy）：已知的专业词汇蓝色Arial字体加下划线（例如electromagnetism）：新学的专业词汇黑色Times New Roman字体加下划线（例如postulate）：新学的普通词汇1 Physics 物理学1 Physics 物理学Introduction to physicsPhysics is a part of natural philosophy and a natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Over the last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and biology, but during the Scientific Revolution in the 17th century, the natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry,and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms of other sciences, while opening new avenues of research in areas such as mathematics and philosophy.Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.Core theoriesThough physics deals with a wide variety of systems, certain theories are used by all physicists. Each of these theories were experimentally tested numerous times and found correct as an approximation of nature (within a certain domain of validity).For instance, the theory of classical mechanics accurately describes the motion of objects, provided they are much larger than atoms and moving at much less than the speed of light. These theories continue to be areas of active research, and a remarkable aspect of classical mechanics known as chaos was discovered in the 20th century, three centuries after the original formulation of classical mechanics by Isaac Newton (1642–1727) 【艾萨克·牛顿】.University PhysicsThese central theories are important tools for research into more specialized topics, and any physicist, regardless of his or her specialization, is expected to be literate in them. These include classical mechanics, quantum mechanics, thermodynamics and statistical mechanics, electromagnetism, and special relativity.Classical and modern physicsClassical mechanicsClassical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, acoustics, optics, thermodynamics, and electromagnetism.Classical mechanics is concerned with bodies acted on by forces and bodies in motion and may be divided into statics (study of the forces on a body or bodies at rest), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); mechanics may also be divided into solid mechanics and fluid mechanics (known together as continuum mechanics), the latter including such branches as hydrostatics, hydrodynamics, aerodynamics, and pneumatics.Acoustics is the study of how sound is produced, controlled, transmitted and received. Important modern branches of acoustics include ultrasonics, the study of sound waves of very high frequency beyond the range of human hearing; bioacoustics the physics of animal calls and hearing, and electroacoustics, the manipulation of audible sound waves using electronics.Optics, the study of light, is concerned not only with visible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light.Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy.Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamics with moving charges, and magnetostatics with magnetic poles at rest.Modern PhysicsClassical physics is generally concerned with matter and energy on the normal scale of1 Physics 物理学observation, while much of modern physics is concerned with the behavior of matter and energy under extreme conditions or on the very large or very small scale.For example, atomic and nuclear physics studies matter on the smallest scale at which chemical elements can be identified.The physics of elementary particles is on an even smaller scale, as it is concerned with the most basic units of matter; this branch of physics is also known as high-energy physics because of the extremely high energies necessary to produce many types of particles in large particle accelerators. On this scale, ordinary, commonsense notions of space, time, matter, and energy are no longer valid.The two chief theories of modern physics present a different picture of the concepts of space, time, and matter from that presented by classical physics.Quantum theory is concerned with the discrete, rather than continuous, nature of many phenomena at the atomic and subatomic level, and with the complementary aspects of particles and waves in the description of such phenomena.The theory of relativity is concerned with the description of phenomena that take place in a frame of reference that is in motion with respect to an observer; the special theory of relativity is concerned with relative uniform motion in a straight line and the general theory of relativity with accelerated motion and its connection with gravitation.Both quantum theory and the theory of relativity find applications in all areas of modern physics.Difference between classical and modern physicsWhile physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match their predictions.Albert Einstein【阿尔伯特·爱因斯坦】contributed the framework of special relativity, which replaced notions of absolute time and space with space-time and allowed an accurate description of systems whose components have speeds approaching the speed of light.Max Planck【普朗克】, Erwin Schrödinger【薛定谔】, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales.Later, quantum field theory unified quantum mechanics and special relativity.General relativity allowed for a dynamical, curved space-time, with which highly massiveUniversity Physicssystems and the large-scale structure of the universe can be well-described. General relativity has not yet been unified with the other fundamental descriptions; several candidate theories of quantum gravity are being developed.Research fieldsContemporary research in physics can be broadly divided into condensed matter physics; atomic, molecular, and optical physics; particle physics; astrophysics; geophysics and biophysics. Some physics departments also support research in Physics education.Since the 20th century, the individual fields of physics have become increasingly specialized, and today most physicists work in a single field for their entire careers. "Universalists" such as Albert Einstein (1879–1955) and Lev Landau (1908–1968)【列夫·朗道】, who worked in multiple fields of physics, are now very rare.Condensed matter physicsCondensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of particles in a system is extremely large and the interactions between them are strong.The most familiar examples of condensed phases are solids and liquids, which arise from the bonding by way of the electromagnetic force between atoms. More exotic condensed phases include the super-fluid and the Bose–Einstein condensate found in certain atomic systems at very low temperature, the superconducting phase exhibited by conduction electrons in certain materials,and the ferromagnetic and antiferromagnetic phases of spins on atomic lattices.Condensed matter physics is by far the largest field of contemporary physics.Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term condensed matter physics was apparently coined by Philip Anderson when he renamed his research group—previously solid-state theory—in 1967. In 1978, the Division of Solid State Physics of the American Physical Society was renamed as the Division of Condensed Matter Physics.Condensed matter physics has a large overlap with chemistry, materials science, nanotechnology and engineering.Atomic, molecular and optical physicsAtomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions on the scale of single atoms and molecules.1 Physics 物理学The three areas are grouped together because of their interrelationships, the similarity of methods used, and the commonality of the energy scales that are relevant. All three areas include both classical, semi-classical and quantum treatments; they can treat their subject from a microscopic view (in contrast to a macroscopic view).Atomic physics studies the electron shells of atoms. Current research focuses on activities in quantum control, cooling and trapping of atoms and ions, low-temperature collision dynamics and the effects of electron correlation on structure and dynamics. Atomic physics is influenced by the nucleus (see, e.g., hyperfine splitting), but intra-nuclear phenomena such as fission and fusion are considered part of high-energy physics.Molecular physics focuses on multi-atomic structures and their internal and external interactions with matter and light.Optical physics is distinct from optics in that it tends to focus not on the control of classical light fields by macroscopic objects, but on the fundamental properties of optical fields and their interactions with matter in the microscopic realm.High-energy physics (particle physics) and nuclear physicsParticle physics is the study of the elementary constituents of matter and energy, and the interactions between them.In addition, particle physicists design and develop the high energy accelerators,detectors, and computer programs necessary for this research. The field is also called "high-energy physics" because many elementary particles do not occur naturally, but are created only during high-energy collisions of other particles.Currently, the interactions of elementary particles and fields are described by the Standard Model.●The model accounts for the 12 known particles of matter (quarks and leptons) thatinteract via the strong, weak, and electromagnetic fundamental forces.●Dynamics are described in terms of matter particles exchanging gauge bosons (gluons,W and Z bosons, and photons, respectively).●The Standard Model also predicts a particle known as the Higgs boson. In July 2012CERN, the European laboratory for particle physics, announced the detection of a particle consistent with the Higgs boson.Nuclear Physics is the field of physics that studies the constituents and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those in nuclear medicine and magnetic resonance imaging, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology.University PhysicsAstrophysics and Physical CosmologyAstrophysics and astronomy are the application of the theories and methods of physics to the study of stellar structure, stellar evolution, the origin of the solar system, and related problems of cosmology. Because astrophysics is a broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.The discovery by Karl Jansky in 1931 that radio signals were emitted by celestial bodies initiated the science of radio astronomy. Most recently, the frontiers of astronomy have been expanded by space exploration. Perturbations and interference from the earth's atmosphere make space-based observations necessary for infrared, ultraviolet, gamma-ray, and X-ray astronomy.Physical cosmology is the study of the formation and evolution of the universe on its largest scales. Albert Einstein's theory of relativity plays a central role in all modern cosmological theories. In the early 20th century, Hubble's discovery that the universe was expanding, as shown by the Hubble diagram, prompted rival explanations known as the steady state universe and the Big Bang.The Big Bang was confirmed by the success of Big Bang nucleo-synthesis and the discovery of the cosmic microwave background in 1964. The Big Bang model rests on two theoretical pillars: Albert Einstein's general relativity and the cosmological principle (On a sufficiently large scale, the properties of the Universe are the same for all observers). Cosmologists have recently established the ΛCDM model (the standard model of Big Bang cosmology) of the evolution of the universe, which includes cosmic inflation, dark energy and dark matter.Current research frontiersIn condensed matter physics, an important unsolved theoretical problem is that of high-temperature superconductivity. Many condensed matter experiments are aiming to fabricate workable spintronics and quantum computers.In particle physics, the first pieces of experimental evidence for physics beyond the Standard Model have begun to appear. Foremost among these are indications that neutrinos have non-zero mass. These experimental results appear to have solved the long-standing solar neutrino problem, and the physics of massive neutrinos remains an area of active theoretical and experimental research. Particle accelerators have begun probing energy scales in the TeV range, in which experimentalists are hoping to find evidence for the super-symmetric particles, after discovery of the Higgs boson.Theoretical attempts to unify quantum mechanics and general relativity into a single theory1 Physics 物理学of quantum gravity, a program ongoing for over half a century, have not yet been decisively resolved. The current leading candidates are M-theory, superstring theory and loop quantum gravity.Many astronomical and cosmological phenomena have yet to be satisfactorily explained, including the existence of ultra-high energy cosmic rays, the baryon asymmetry, the acceleration of the universe and the anomalous rotation rates of galaxies.Although much progress has been made in high-energy, quantum, and astronomical physics, many everyday phenomena involving complexity, chaos, or turbulence are still poorly understood. Complex problems that seem like they could be solved by a clever application of dynamics and mechanics remain unsolved; examples include the formation of sand-piles, nodes in trickling water, the shape of water droplets, mechanisms of surface tension catastrophes, and self-sorting in shaken heterogeneous collections.These complex phenomena have received growing attention since the 1970s for several reasons, including the availability of modern mathematical methods and computers, which enabled complex systems to be modeled in new ways. Complex physics has become part of increasingly interdisciplinary research, as exemplified by the study of turbulence in aerodynamics and the observation of pattern formation in biological systems.Vocabulary★natural science 自然科学academic disciplines 学科astronomy 天文学in their own right 凭他们本身的实力intersects相交，交叉interdisciplinary交叉学科的，跨学科的★quantum 量子的theoretical breakthroughs 理论突破★electromagnetism 电磁学dramatically显著地★thermodynamics热力学★calculus微积分validity★classical mechanics 经典力学chaos 混沌literate 学者★quantum mechanics量子力学★thermodynamics and statistical mechanics热力学与统计物理★special relativity狭义相对论is concerned with 关注，讨论，考虑acoustics 声学★optics 光学statics静力学at rest 静息kinematics运动学★dynamics动力学ultrasonics超声学manipulation 操作，处理，使用University Physicsinfrared红外ultraviolet紫外radiation辐射reflection 反射refraction 折射★interference 干涉★diffraction 衍射dispersion散射★polarization 极化，偏振internal energy 内能Electricity电性Magnetism 磁性intimate 亲密的induces 诱导，感应scale尺度★elementary particles基本粒子★high-energy physics 高能物理particle accelerators 粒子加速器valid 有效的，正当的★discrete离散的continuous 连续的complementary 互补的★frame of reference 参照系★the special theory of relativity 狭义相对论★general theory of relativity 广义相对论gravitation 重力，万有引力explicit 详细的，清楚的★quantum field theory 量子场论★condensed matter physics凝聚态物理astrophysics天体物理geophysics地球物理Universalist博学多才者★Macroscopic宏观Exotic奇异的★Superconducting 超导Ferromagnetic铁磁质Antiferromagnetic 反铁磁质★Spin自旋Lattice 晶格，点阵，网格★Society社会，学会★microscopic微观的hyperfine splitting超精细分裂fission分裂，裂变fusion熔合，聚变constituents成分，组分accelerators加速器detectors 检测器★quarks夸克lepton 轻子gauge bosons规范玻色子gluons胶子★Higgs boson希格斯玻色子CERN欧洲核子研究中心★Magnetic Resonance Imaging磁共振成像，核磁共振ion implantation 离子注入radiocarbon dating放射性碳年代测定法geology地质学archaeology考古学stellar 恒星cosmology宇宙论celestial bodies 天体Hubble diagram 哈勃图Rival竞争的★Big Bang大爆炸nucleo-synthesis核聚合，核合成pillar支柱cosmological principle宇宙学原理ΛCDM modelΛ-冷暗物质模型cosmic inflation宇宙膨胀1 Physics 物理学fabricate制造，建造spintronics自旋电子元件，自旋电子学★neutrinos 中微子superstring 超弦baryon重子turbulence湍流，扰动，骚动catastrophes突变，灾变，灾难heterogeneous collections异质性集合pattern formation模式形成University Physics2 Classical mechanics 经典力学IntroductionIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science, engineering and technology.Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. Besides this, many specializations within the subject deal with gases, liquids, solids, and other specific sub-topics.Classical mechanics provides extremely accurate results as long as the domain of study is restricted to large objects and the speeds involved do not approach the speed of light. When the objects being dealt with become sufficiently small, it becomes necessary to introduce the other major sub-field of mechanics, quantum mechanics, which reconciles the macroscopic laws of physics with the atomic nature of matter and handles the wave–particle duality of atoms and molecules. In the case of high velocity objects approaching the speed of light, classical mechanics is enhanced by special relativity. General relativity unifies special relativity with Newton's law of universal gravitation, allowing physicists to handle gravitation at a deeper level.The initial stage in the development of classical mechanics is often referred to as Newtonian mechanics, and is associated with the physical concepts employed by and the mathematical methods invented by Newton himself, in parallel with Leibniz【莱布尼兹】, and others.Later, more abstract and general methods were developed, leading to reformulations of classical mechanics known as Lagrangian mechanics and Hamiltonian mechanics. These advances were largely made in the 18th and 19th centuries, and they extend substantially beyond Newton's work, particularly through their use of analytical mechanics. Ultimately, the mathematics developed for these were central to the creation of quantum mechanics.Description of classical mechanicsThe following introduces the basic concepts of classical mechanics. For simplicity, it often2 Classical mechanics 经典力学models real-world objects as point particles, objects with negligible size. The motion of a point particle is characterized by a small number of parameters: its position, mass, and the forces applied to it.In reality, the kind of objects that classical mechanics can describe always have a non-zero size. (The physics of very small particles, such as the electron, is more accurately described by quantum mechanics). Objects with non-zero size have more complicated behavior than hypothetical point particles, because of the additional degrees of freedom—for example, a baseball can spin while it is moving. However, the results for point particles can be used to study such objects by treating them as composite objects, made up of a large number of interacting point particles. The center of mass of a composite object behaves like a point particle.Classical mechanics uses common-sense notions of how matter and forces exist and interact. It assumes that matter and energy have definite, knowable attributes such as where an object is in space and its speed. It also assumes that objects may be directly influenced only by their immediate surroundings, known as the principle of locality.In quantum mechanics objects may have unknowable position or velocity, or instantaneously interact with other objects at a distance.Position and its derivativesThe position of a point particle is defined with respect to an arbitrary fixed reference point, O, in space, usually accompanied by a coordinate system, with the reference point located at the origin of the coordinate system. It is defined as the vector r from O to the particle.In general, the point particle need not be stationary relative to O, so r is a function of t, the time elapsed since an arbitrary initial time.In pre-Einstein relativity (known as Galilean relativity), time is considered an absolute, i.e., the time interval between any given pair of events is the same for all observers. In addition to relying on absolute time, classical mechanics assumes Euclidean geometry for the structure of space.Velocity and speedThe velocity, or the rate of change of position with time, is defined as the derivative of the position with respect to time. In classical mechanics, velocities are directly additive and subtractive as vector quantities; they must be dealt with using vector analysis.When both objects are moving in the same direction, the difference can be given in terms of speed only by ignoring direction.University PhysicsAccelerationThe acceleration , or rate of change of velocity, is the derivative of the velocity with respect to time (the second derivative of the position with respect to time).Acceleration can arise from a change with time of the magnitude of the velocity or of the direction of the velocity or both . If only the magnitude v of the velocity decreases, this is sometimes referred to as deceleration , but generally any change in the velocity with time, including deceleration, is simply referred to as acceleration.Inertial frames of referenceWhile the position and velocity and acceleration of a particle can be referred to any observer in any state of motion, classical mechanics assumes the existence of a special family of reference frames in terms of which the mechanical laws of nature take a comparatively simple form. These special reference frames are called inertial frames .An inertial frame is such that when an object without any force interactions (an idealized situation) is viewed from it, it appears either to be at rest or in a state of uniform motion in a straight line. This is the fundamental definition of an inertial frame. They are characterized by the requirement that all forces entering the observer's physical laws originate in identifiable sources (charges, gravitational bodies, and so forth).A non-inertial reference frame is one accelerating with respect to an inertial one, and in such a non-inertial frame a particle is subject to acceleration by fictitious forces that enter the equations of motion solely as a result of its accelerated motion, and do not originate in identifiable sources. These fictitious forces are in addition to the real forces recognized in an inertial frame.A key concept of inertial frames is the method for identifying them. For practical purposes, reference frames that are un-accelerated with respect to the distant stars are regarded as good approximations to inertial frames.Forces; Newton's second lawNewton was the first to mathematically express the relationship between force and momentum . Some physicists interpret Newton's second law of motion as a definition of force and mass, while others consider it a fundamental postulate, a law of nature. Either interpretation has the same mathematical consequences, historically known as "Newton's Second Law":a m t v m t p F ===d )(d d dThe quantity m v is called the (canonical ) momentum . The net force on a particle is thus equal to rate of change of momentum of the particle with time.So long as the force acting on a particle is known, Newton's second law is sufficient to。

Reduction of NO x by H 2on Pt/WO 3/ZrO 2catalysts in oxygen-rich exhaustF.J.P.Schott,P.Balle,J.Adler,S.Kureti *Institut fu¨r Technische Chemie und Polymerchemie,Universita ¨t Karlsruhe,Kaiserstrasse 12,D-76128Karlsruhe,Germany 1.IntroductionNitrogen oxides (NO x )emitted by lean-burn engines con-tribute to various environmental problems,for instance forma-tion of acid rain as well as ozone.As a consequence,the emission limits have been worldwide tightened in the past.For the removal of NO x from oxygen-rich exhaust the selective catalytic reduction (SCR)using NH 3and NO x storage reduction catalyst (NSR)are currently the most favoured technologies.However,a serious constraint of these techniques is the minor deNO x performance below 2008C.Contrary,the catalytic reduction of NO x by H 2(H 2-deNO x )reveals an interesting potential for the low-temperature NO x abatement being particularly crucial for diesel passenger cars.In the driving cycle of the European Union the exhaust temperature is below 1508C for about 60%of cycle time.Thus,SCR and NSR do not cover the most part of the certification cycle and might therefore come under pressure when the exhaust limits will be markedly tightened in the future.This clearly indicates the need for a deNO x technique operating at low temperatures.Furthermore,low-temperature NO x reduction exhibits a potential for industrial applications as well, e.g.for fossil power plants,waste combustion plants,nitric acid production and air separation.First published in 1971Jones et al.show the effective NO x reduction by H 2in slight excess of O 2using a Pt/Al 2O 3catalyst [1].High NO x conversions are observed between 65and 2008C while indicating a high yield of nitrous oxide as well;at maximum deNO x the molar ratio of N 2/N 2O is shown to be unity.The mechanism of the reaction of NO with H 2on Pt/Al 2O 3involves the reduction of the active Pt sites by H 2followed by adsorption and dissociation of NO [2].The recombination of two N atoms leads to the formation of N 2,whereas the oxygen is retained onto the Pt surface.Contrary,N 2O is produced by combination of a N atom and NO being adsorbed on neighbouring Pt sites.In the last years some Pt H 2-deNO x catalysts are presented revealing considerable low-temperature activity even under strongly oxidising conditions [3–6].Wildermann reports on a very active Pt/Al 2O 3catalyst that shows maximum performance already at 708C [3].However,this material produces a huge proportion of N 2O being in line with the results from Jones et al.[1].For example,at peak NO x conversion the N 2O selectivity amounts to 80%.Moreover,Wildermann indicates the enhancement of activity and N 2production of Pt/Al 2O 3by using the promoter Mo (3.4wt.%)resulting in a N 2selectivity of 40%.The performance of this Pt/Mo/Al 2O 3catalyst is additionally enhanced by Co,whereas the N 2selectivity is slightly increased only.However,the activityApplied Catalysis B:Environmental 87(2009)18–29A R T I C L E I N F O Article history:Received 30June 2008Received in revised form 19August 2008Accepted 26August 2008Available online 31August 2008Keywords:NO x reduction H 2Pt WO 3ZrO 2Diesel exhaust Mechanism DRIFTSA B S T R A C TThis work addresses the low-temperature NO x abatement under oxygen-rich conditions using H 2as reductant.For this purpose Pt/ZrO 2and Pt/WO 3/ZrO 2catalysts are developed and characterised by temperature-programmed desorption of H 2(H 2-TPD),N 2physisorption (BET)and powder X-ray diffraction (PXRD).The most active catalyst is a Pt/WO 3/ZrO 2pattern with a Pt load of 0.3wt.%and a W content of 11wt.%.This material reveals high deNO x activity below 2008C and high overall N 2selectivity of about 90%.Additionally,the catalyst exhibits outstanding hydrothermal stability as well as resistance against SO x .Furthermore,the transfer from the powder level to real honeycomb systems leads to promising performance as well.Diffuse reflectance Fourier transform infrared spectroscopic studies,kinetic modelling of tempera-ture-programmed desorption of O 2(O 2-TPD)and NO x -TPD examinations indicate that the pronounced H 2-deNO x performance of the Pt/WO 3/ZrO 2catalyst is related to the electronic interaction of WO 3with the precious metal.The tungsten promoter increases the electron density on the Pt thus activating the sample for H 2-deNO x and N 2formation,respectively.Contrary,NO x surface species formed on the WO 3/ZrO 2support are not supposed to be involved in the H 2-deNO x reaction.ß2008Elsevier B.V.All rights reserved.*Corresponding author.Tel.:+497216088090;fax:+497216082816.E-mail address:kureti@ict.uni-karlsruhe.de (S.Kureti).Contents lists available at ScienceDirectApplied Catalysis B:Environmentalj o ur n a l h o m e p a g e :w w w.e l se v i e r.c om /l oc a t e /a p c a t b0926-3373/$–see front matter ß2008Elsevier B.V.All rights reserved.doi:10.1016/j.apcatb.2008.08.021declines when CO exceeds0.15vol.%[7,8]being in accordance with Lambert and Macleod[9,10].Costa et al.report a Pt/La0.7Sr0.2Ce0.1FeO3catalyst with pronounced low-temperature activity as well as substantially increased N2selectivity up to80–90%[11,12].Detailed examina-tions performed with a related Pt/La0.5Sr0.2Ce0.51MnO3sample[12] indicate a different reaction mechanism as compared to that elucidated for Pt/Al2O3[2].Costa et al.postulate chemisorption of NO x on the support resulting in nitro and nitrato surface species, while H2adsorbs dissociatively on the Pt component.Then,the atomic hydrogen spills over to the support reducing the NO x surface complexes to release N2and H2O.Following Costa et al.this mechanism suppresses the formation of N2O.A very similar mechanism is postulated for a Pt/MgO–CeO2catalyst being very active as well[13,14].In contrast to platinum,Ru,Ir,Rh,Pd and Ag [3,15]as well as perovskite catalysts[11,16–18]reveal no or at least low performance in excess of O2.An exception is Pd/LaCoO3 showing considerable activity[19].Furthermore,it is worth mentioning that the H2-deNO x reaction is an important feature of the TWC technology as well as in regeneration of NSR catalystsreducing NO x under stoichiometric and rich conditions,respec-tively.The aim of this paper is the development of a H2-deNO x catalyst showing both pronounced low-temperature activity and minimum N2O production,whereas the present study mainly focuses on diesel exhaust.For this purpose a series of Pt/ZrO2and Pt/WO3/ ZrO2samples is systematically prepared,characterised andfinally tested for H2-deNO x.These systems are selected as a result of pre-studies in which different support materials have been screened [20,21],e.g.Al2O3,SiO2,ZrO2,TiO2and MgO carriers all modified with alkaline and alkaline earth metals,elements of the1st period of transition metals,Ce,La and Mo.For the evaluation of the technical potential of the most promising catalyst relevant conditions are varied,while a coated honeycomb is employed as well.Additionally,mechanistic examinations are performed to gain insight into the effectiveness of the best catalyst.2.Experimental2.1.Development of the ZrO2support and catalyst preparationPreliminary catalytic investigations show that the synthesis route,crystalline phase and BET surface area of the ZrO2substrate strongly affect the performance of the H2-deNO x catalysts[22].The best result is obtained with a self-prepared zirconia existing in the tetragonal phase.This material is synthesised by advancing the so-called hydrazine route[23,24]providing reliable product quality and sufficient mass to coat several full size honeycombs for automotive applications.For the synthesis a solution of234g ZrO(NO3)2(Fluka)in 1.6l distilled H2O is added to a boiling mixture of400ml N2H4ÁH2O(Fluka)and1.2l distilled H2O.The resulting blend is digested for12h under reflux,whereas shorter reaction time leads to unwanted monoclinic ZrO2as well(Fig.1). Afterfiltration and washing with H2O the solid is dried overnight at 1008C and calcined in air at7508C for6h.The yield of ZrO2is almost100%(85g).The introduction of Pt is carried out by incipient wetness method.In this impregnation a defined volume of Pt(NO3)2 (Chempur)solution is taken such that it is completely absorbed by the substrate.The adjusted Pt loads referring to the support range from0.1to2.0wt.%.After impregnation,the samples are dried overnight at1008C and are then activated by dosing a gas mixture of9vol.%H2and91vol.%N2.In the activation step the temperature is increased from20to3008C at the rate of1.0K minÀ1;the end temperature is held for30min.Finally,the samples are condi-tioned by heating in air at5008C for5h.For reference purposes a classical Pt/Al2O3catalyst is also prepared taking commercially available g-Al2O3balls(d=0.6mm,Sasol).The modification of ZrO2with tungsten is performed by incipient wetness method as well using a solution of (NH4)6H2W12O41(Fluka).Different loads of W(up to22wt.%) relating to the mass of ZrO2are established by varying the concentration of(NH4)6H2W12O41.After impregnation,the sample is dried overnight at1008C and is then impregnated by Pt as mentioned above.It is worth noting that in the H2activation tungsten oxide is not reduced[24].2.2.Characterisation of the catalystsCrystalline phase of the pure supports as well as catalysts is examined by powder X-ray diffraction(PXRD).The PXRD patterns are recorded at room temperature on a Siemens D501using Ni filtered Cu K a radiation.A2u step size of0.028is used with an integration time of4s.The diffractogram of the commercial Al2O3 carrier confirms the g-modification,while the prepared ZrO2is in the tetragonal phase as already demonstrated in Fig.1.Regardless of the load of W no reflexes of crystalline tungsten oxide are observed suggesting amorphous WO x domains,at least at W contents above6wt.%when tungsten oxide exists in sufficient abundance to be monitored.Additionally,signals of Pt are not found as well being associated with its low contents.The dispersion of Pt is studied by temperature-programmed desorption of H2(H2-TPD).In these analyses,same laboratory bench is used as in the catalytic investigations(Section2.4).Respective sample(1.5g)is charged into the quartz glass tube reactor(i.d. 8mm)and pre-treated in Arflow at6008C for15min.Subsequently, the catalyst is cooled to3008C and exposed to a gas mixture of 5vol.%H2and95vol.%Ar for30min to reduce the active Pt surface. The pattern is then rapidly cooled to308C in the H2/Arflow.After saturation,it isflushed with Ar and H2-TPD is started using Ar as carrier gas(100ml minÀ1,STP).In TPD the catalyst is heated to 6008C at the rate of20K minÀ1,whereupon temperature is recorded by a K type thermocouple(TC)fitted directly in front of the sample. Desorbing H2is continuously monitored by thermal conductivity detection(TCD,Shimadzu).For specific analysis of H2the reactor effluents pass a cold trap(À508C)removing H2O.The Pt dispersion (d Pt)is determined by supposing that one H adsorbs per active Pt site (Eq.(1))[25].The molar amount of desorbing H2ðn H2Þis obtained by integrating the corresponding TCD signal,whereas the total proportion of Pt(n Pt)is known from the impregnationprocedure. Fig.1.PXRD patterns of the prepared ZrO2support depending on the digestion time (a)5min,(b)1h,(c)4h,(d)7h,(e)12h and(f)17h;*monoclinic phase;+ tetragonal phase);final calcination is performed in air at7508C for6h;analytical parameters of PXRD are described in next section.F.J.P.Schott et al./Applied Catalysis B:Environmental87(2009)18–2919As derived from blank experiments,e.g.Pt free 11W/ZrO 2,the H 2desorption is specific for Pt.d Pt ¼0:5n H 2n Pt(1)Furthermore,the ZrO 2-based catalyst with a Pt load of 0.3wt.%and a W content of 11wt.%is exemplarily characterised by X-ray photoelectron spectroscopy.The spectrometer is a Phoibos 150MCD from Specs being equipped with a Mg anode (E (Mg K a )=1253eV).The spectrum shows a clear absorption at 36eV (W4f 7/2)being related to W 6+species [26].The BET surface area of the catalysts is investigated by multi-point Sorptomatic 1990using N 2as adsorbate.The BET data are listed in Table 1along with the loading,Pt dispersion and sample codes.It is worth mentioning that the declining BET surface area of the 0.3Pt/W/ZrO 2samples is mainly related to the increasing proportion of WO 3exhibiting negligible surface area and it is not due to the blocking of pores of the ZrO 2carrier.2.3.O 2-and NO x -TPD studiesO 2-TPD studies are performed to investigate the kinetics of the adsorption and desorption of O 2on selected catalysts.Oxygen is used as probe molecule since it represents a dominating species on the Pt surface under lean burn conditions [27].The procedure of O 2-TPD is similar to that described above for H 2-TPD.The catalyst (5.00g)is heated in Ar at 7508C for 15min,cooled to 508C and is then exposed to a mixture of 2vol.%O 2and 98vol.%Ar (99.996%,<6ppm O 2)until the sample is saturated.After flushing with Ar (500ml min À1,STP)TPD is started with a rate of 20K min À1.O 2is detected by CIMS (Airsense 500,V &F).As the axial and radial temperature gradients along the catalyst bed are below 10K heat transfer effects are to be neglected.Furthermore,Mears and Weisz Prater criteria [28],that amount to 10À5and 10À2,respectively,exclude transport limitation by film and pore diffusion.NO x -TPD examinations are conducted similar to H 2-TPD as well using a catalyst mass of 1.50g.After the pre-treatment performed at 5008C the sample is cooled to 1258C in Ar flow and is then exposed to a mixture of 2800ppm NO and 6vol.%O 2in Ar.In this treatment NO is partially converted into NO 2(15%)due to catalytic oxidation.After saturation,the dosage of NO and O 2is stopped and the reactor is flushed by Ar followed by starting the TPD with a rateof 20K min À1.Additionally,before beginning the TPD a mixture of (a)1500ppm H 2,6vol.%O 2,Ar (balance)or (b)1500ppm H 2in Ar is added for 10min to study the reaction of NO x surface species with H 2.Subsequently,it is purged again and TPD is finally started employing exclusively the CLD analyzer mentioned in the following section.2.4.H 2-deNO x studiesThe catalytic investigations are performed on a laboratory bench using a diesel model exhaust.Before the measurements,the samples are pressed to pellet with 40MPa,granulated and sieved in a mesh size of 125–250m m;an exception is the Pt/Al 2O 3pattern which is kept in form of balls.The samples (1.50g)are charged into the quartz glass tube reactor (i.d.8mm),fixed with quartz wool and pre-treated in Ar flow at 5008C for 15min to remove possible impurities and to provide reproducible conditions.Subsequently,the model exhaust is added and the temperature is decreased to 408C with a rate (b )of 1.0K min À1.Furthermore,some experi-ments are carried out under stationary conditions at selected temperatures.The standard feed (500ml min À1,STP)is composed of 500ppm NO,2000ppm H 2,6.0vol.%O 2and Ar as balance.To evaluate the best catalyst the concentration of H 2and O 2is varied and other relevant exhaust gas species,i.e.CO,H 2O and CO 2are dosed additionally.The feed is obtained by blending a special mixture of 2000ppm H 2and 6.0vol.%O 2in Ar with the other components (Air Liquide).The flow of each component is controlled by independent mass flow controllers (MKS Instru-ments),whereas water is supplied by a liquid pump (Kronlab).Temperature is measured by a K type TC located directly in front of and behind the catalyst ing the standard feed the temperature difference between inlet and outlet is below 10K and therefore only the inlet temperature is presented.The analysis of NO x is conducted by means of CLD (EL-ht,Eco Physics),while N 2O,CO and CO 2are monitored by NDIR spectroscopy (Uras 10E,Hartmann &Braun).N 2is detected by GC/TCD (RGC 202withpacked columns Haye Sep Q 60and mol sieve 5A˚,Siemens)resulting in a time resolution of 9min that corresponds to a temperature interval of 15K.Oxygen is analysed by using magnetomechanics (Magnos 6G,Hartmann &Braun).The NO x conversion (X (NO x ))refers to the formation of N 2and N 2O as defined by Eq.(2),whereas the temperature programmed H 2-deNO x data are found to be equal to stationary results.For the major part of the reaction the mass of N is balanced being associated with the production of N 2and N 2O thus excluding the genesis of NH 3.Nevertheless,below 808C H 2-deNO x is slightly interfered by NO x adsorption corresponding to less than 10%conversion.X ðNO x Þ¼2c ðN 2Þþ2c ðN 2O Þc ðNO x Þin(2)The selectivity of N 2(S (N 2))is defined by Eq.(3),whereupon a corresponding expression is used for the N 2O selectivity (S (N 2O)).Moreover,for the comparison of different catalysts the overall selectivity of N 2(S (N 2)overall )is taken as well (Eq.(4));T 1and T 2are the temperatures with NO x conversion of 20%.Selectivity data are exclusively presented for deNO x above 20%to minimise error propagation.S ðN 2Þ¼c ðN 2Þ22(3)S ðN 2Þoverall ¼ZT 2T 1S ðN 2Þd T21(4)Table 1Load of Pt and W,sample code,BET surface area and Pt dispersion of the H 2-deNO x catalysts Catalyst system m(Pt)(%)m(W)(%)Sample codeS BET(m 2g À1)d Pt (%)Pt/Al 2O 30.50.5Pt/Al 2O 3150522Pt/Al 2O 31489Pt/ZrO 20.10.1Pt/ZrO 299300.30.3Pt/ZrO 2100250.50.5Pt/ZrO 21003622Pt/ZrO 29811Pt/WO 3/ZrO 2a0.330.3Pt/3W/ZrO 297360.360.3Pt/6W/ZrO 2106500.3110.3Pt/11W/ZrO 268900.3220.3Pt/22W/ZrO 26295b 2112Pt/11W/ZrO 27011aThe loads of Pt and W refer to the ZrO 2support.bWhile the Pt dispersion of 0.3Pt/11W/ZrO 2is checked by HRTEM (particles <2nm),double H 2desorption is observed for 0.3Pt/22W/ZrO 2.Hence,different H/Pt stoichiometry is assumed being speculated to be 2.This change might be associated with Pt–W interactions dominating at high tungsten oxide coverages amounting to ca.45%for 22%W.F.J.P.Schott et al./Applied Catalysis B:Environmental 87(2009)18–29202.5.DRIFTS studiesThe DRIFT spectroscopic studies are performed with a Nicolet 5700FTIR spectrometer(Thermo Electron)being equipped with a MCT detector and DRIFTS optics(Thermo Mattson).The sample compartment is continuously purged with N2to avoid diffusion of air.The IR cell made of stainless steel contains a ZnSe window and is connected to a gas-handling system.The spectra are recorded in the range from1000to4000cmÀ1with an instrument resolution of 4cmÀ1.100scans are accumulated to a spectrum resulting in a time resolution of1min.Before the analysis,the catalyst powder is charged into the sample holder of the cell and is heated for30min at 5008C in N2or Arflow(500ml minÀ1,STP).In the studies using CO as probe molecule the sample is then exposed at2508C for30min to a mixture of2000ppm H2and6vol.%O2(N2balance);this is done to establish similar conditions as in catalytic studies(Section2.4). Subsequently,the catalyst is cooled in N2flow to258C and then a background spectrum is recorded.After this,the sample is treated for5min with a mixture of500ppm CO in N2followed by purging with N2.Finally,the sample spectrum is collected.The DRIFTS investigation of H2-deNO x is performed sequen-tially.Firstly,the catalyst is cooled from500to1258C under flowing Ar and then the background spectrum is taken.Subse-quently,the sample is exposed for10min to a mixture of 1000ppm NO and6vol.%O2(Ar balance)followed by purging with Ar and taking the spectrum.After this,the blend of40or2000ppm H2and6vol.%O2(Ar balance)is added while continuously collecting data.The H2concentration of40ppm is adjusted to definitely avoid hot spots on the catalyst.The DRIFT spectra are presented in terms of Kubelka Munk transformation defined as F(R)=(1ÀR)2/(2R)with R=R s/R r, whereas R s is the reflectance of the sample under reaction conditions and R r that under the Arflow.3.Results and discussion3.1.Performance of the Pt/Al2O3reference and the Pt/ZrO2catalystsA preliminary investigation performed in the absence of a catalyst shows no conversion of NO x excluding H2-deNO x by gas-phase reactions.In contrast to that,the0.5Pt/Al2O3referencereveals pronounced low-temperature activity,whereas the opera-tion window is rather narrow(50–1508C)and N2O forms as the major product;S(N2)overall amounts to20%(Fig.2).The perfor-mance of Pt/Al2O3is considered to be in fair agreement with literature addressing the same catalytic system[1,3,4].Fig.3illustrates the performance of0.3Pt/ZrO2indicating NO x conversion in the entire temperature range with two deNO x maxima at140and1708C.Furthermore,the peak NO x removal is higher as compared to0.5Pt/Al2O3.Another interesting feature is the markedly improved N2selectivity of0.3Pt/ZrO2,i.e.N2is formed as the major product showing an overall selectivity of55%.The Pt/ZrO2samples with Pt contents of0.1and0.5wt.%show similar peak NO x conversions of78and82%,respectively,whereas their operation range is restricted covering a range of ca.140K only.Furthermore,S(N2)overall is very similar to0.3Pt/ZrO2.Hence, the latter material is considered to be superior and is therefore adopted to the Pt/WO3/ZrO2system.The superiority of0.3Pt/ZrO2 is difficult to explain as Table1shows very similar physical–chemical properties for the Pt/ZrO2samples.3.2.Performance of the0.3Pt/W/ZrO2catalystsFor comparison of the0.3Pt/W/ZrO2samples revealing different loads of W the maximum NO x conversion(X(NO x)max)is used in addition to S(N2)overall.Fig.4shows that a little amount of tungsten is sufficient to increase deNO x as well as N2selectivity.The optimum content of W is11wt.%resulting in an overall N2 selectivity of85%and a peak NO x conversion of95%;assuming planar tungsten oxide the ZrO2coverage by WO3is estimated to be 0.22being significantly less than a monolayer.Furthermore,the results of XPS and PXRD suggest that the tungsten component exists in the form of amorphous WO3.For clarity the performance of the0.3Pt/11W/ZrO2catalyst is presented in Fig.5.The data point to a broad range of deNO x with two conversion peaks at90and2508C.As a consequence,0.3Pt/ 11W/ZrO2covers the low-as well as high-temperature regime thus representing a promising catalytic material.Nevertheless,it should be stated that the low-temperature activity is much more pronounced,while above2508C deNO x declines.The latter feature is attributed to increasing conversion of H2with O2being present in excess;a more detailed discussion of the educt selectivity is presented in Section3.4.The two NO x conversion maximums are ascribed to different active Pt sites as stated in Section 3.5.3, whereas no evidence for active NO x species located on the support is found as discussed in Section3.5.3as well.Contrary,the bare 11W/ZrO2support does not directly participate in deNO x as deduced from a measurement without Pt.However,0.3Pt/11W/ ZrO2still shows significant formation of N2O below1508C,e.g.at Fig.2.H2-deNO x performance of0.5Pt/Al2O3(X(NO x)—,S(N2)--,S(N2O)). Conditions:m=1.50g,c(NO)=500ppm,c(H2)=2000ppm,c(O2)=6.0vol.%,Ar balance,F=500ml minÀ1(STP),S.V.=22.000hÀ1,b=1.0K minÀ1.Fig.3.H2-deNO x performance of0.3Pt/ZrO2(X(NO x)—,S(N2)--,S(N2O)). Conditions:m=1.50g,c(NO)=500ppm,c(H2)=2000ppm,c(O2)=6.0vol.%,Ar balance,F=500ml minÀ1(STP),S.V.=22,000hÀ1,b=1.0K minÀ1.F.J.P.Schott et al./Applied Catalysis B:Environmental87(2009)18–2921the low-temperature deNO x peak S (N 2O)is about 45%.In contrast to that,N 2O is substantially suppressed above 2008C correspond-ing to a N 2selectivity of approximately 90%.Furthermore,it should be mentioned that no NH 3forms in H 2-deNO x on the 0.3Pt/11W/ZrO 2catalyst as referred from a NDIR analysis (Binos 1.1,Leybold-Heraeus).The suppression of NH 3formation is reported to be typical for NO x reduction by H 2on Pt catalysts under oxygen-rich conditions [1].The turnover frequency (TOF)being defined as the number of converted NO x molecules per Pt atom and time is 8.0Â10À3s À1for the deNO x peak at 90%and 5.0Â10À3s À1for the 2508C maximum.These specific H 2-deNO x data are very close to that of 0.1Pt/MgO–CeO 2showing a TOF of ca.8Â10À3s À1(908C)in a similar NO/H 2/O 2feed [14].A direct comparison of the activity range of both catalysts is problematic as data recorded under analogue condi-tions are not available in the study of 0.1Pt/MgO–CeO 2[14].3.3.Evaluation of the 0.3Pt/11W/ZrO 2catalyst3.3.1.Effect of O 2and CO on H 2-deNO x performanceThe previous section provides evidence that the content of O 2is a crucial parameter for the H 2-deNO x reaction.Hence,theeffect of O 2is systematically investigated,whereas for simplicity the performance of 0.3Pt/11W/ZrO 2is exemplarily illustrated at 1258C being representative for the low-temperature range (Fig.6).It is apparent that the O 2concentration does not drastically affect the low-temperature activity, e.g.deNO x is about 90%for 1.5vol.%O 2and ca.75%for 18vol.%.Moreover,the N 2selectivity does not change at all.On the contrary,the high-temperature activity declines markedly with growing O 2content being completely suppressed above 12vol.%O 2(Fig.7).This effect is referred to the increasing reaction of H 2with O 2(Section 3.4).However,diesel engines provide low temperatures in connection with rather high O 2concentrations and vice versa,e.g.at 1508C the O 2content is in the range of 10–15vol.%.Therefore,the decline in high-temperature deNO x observed for relatively high O 2contents is not a substantial issue for practical application.Furthermore,the effect of CO on H 2-deNO x is investigated as well,since this component is known to block active Pt sites at low temperatures which might affect the performance of 0.3Pt/11W/ZrO 2[27].For this examination two representative CO concentra-tions are supplied,i.e.a rather low (40ppm)and a rather high one (400ppm).Fig.8shows that the latter CO concentrationcausesFig.4.Effect of W load on the H 2-deNO x performance of the 0.3Pt/W/ZrO 2samples (X (NO x )max *,S (N 2)overall *).Conditions:m =1.50g,c (NO)=500ppm,c (H 2)=2000ppm,c (O 2)=6.0vol.%,Ar balance,F =500ml min À1(STP),S.V.=22.000h À1,b =1.0K min À1.Fig.5.H 2-deNO x performance of 0.3Pt/11W/ZrO 2(X (NO x )—,S (N 2)--,S (N 2O)).Conditions:m =1.50g,c (NO)=500ppm,c (H 2)=2000ppm,c (O 2)=6.0vol.%,Ar balance,F =500ml min À1(STP),S.V.=22.000h À1,b =1.0K min À1.Fig.6.Effect of O 2on the H 2-deNO x performance of 0.3Pt/11W/ZrO 2at 1258C (X (NO x )*,S (N 2)*).Conditions:m =1.50g,c (NO)=500ppm,c (H 2)=2000ppm,c (O 2)=1.5–18vol.%,Ar balance,F =500ml min À1(STP),S.V.=22.000h À1,b =1.0K min À1.Fig.7.H 2-deNO x performance of 0.3Pt/11W/ZrO 2with a O 2content of 12vol.%(X (NO x )—,S (N 2)--,S (N 2O)).Conditions:m =1.50g,c(NO)=500ppm,c (H 2)=2000ppm,c (O 2)=12vol.%,Ar balance,F =500ml min À1(STP),S.V.=22.000h À1,b =1.0K min À1.F.J.P.Schott et al./Applied Catalysis B:Environmental 87(2009)18–2922a drastic decline in catalytic activity,whereupon significant deNO x begins in parallel to the CO light-off (ca.1108C).This effect is in line with the literature which shows the appearance of free Pt sites being capable of reducing NO only when CO removal starts [29].Consequently,as deNO x is inhibited below 1108C no substantial quantity of N 2O is formed resulting in an overall N 2selectivity of about 90%.Additionally,it is worth mentioning that four maxima of NO x conversion appear pointing to a broad variety of active Pt sites.Furthermore,the CO concentration of 40ppm does not affect the performance of 0.3Pt/11W/ZrO 2at all.These results clearly show that high CO concentrations have to be avoided in practice to maintain H 2-deNO x .Indeed,this can be simply achieved by using a diesel oxidation catalyst (DOC)located in front the H 2-deNO x catalyst.DOC systems are a state-of-the-art technology and are applied in every diesel vehicle released in the industry countries oxidising CO and HC close to the engine outlet.3.3.2.Hydrothermal stability and resistance against SO xFor the use of 0.3Pt/11W/ZrO 2in diesel exhaust its hydrothermal resistance as well as chemical stability towards SO x is of particular concern.To pursue these requirements the catalyst (1.50g)is hydrothermally aged at 7808C for 15h adjusting a gas mixture of 2.5vol.%H 2O and 97.5vol.%Ar (500ml/min,STP),whereas exposure to SO x is carried out at 3508C for 24h while supplying a blend of 40ppm SO 2and synthetic air (500ml min À1,STP).The latter conditions are considered to be appropriate to form SO 3on the catalyst being a strong catalyst poison [30].Nevertheless,both aging procedures do not affect the catalytic performance at all evidencing high resistance of 0.3Pt/11W/ZrO 2against hydrothermal and sulphur exposure.parison of the reducing efficiency of H 2with C 3H 6and COTo assess the efficiency of H 2in the deNO x reaction on 0.3Pt/11W/ZrO 2additional reductants are used.For this purpose C 3H 6and CO are taken as they are potentially formed as major or side product in the on-board production of H 2from diesel,e.g.by catalytic cracking,catalytic partial oxidation or catalytic steam reforming [31];C 3H 6is taken as a model hydrocarbon.For an accurate comparison 10,000ppm H 2,1000ppm C 3H 6or 9000ppm CO are dosed to the standard feed.These concentra-tions demand very similar amount of oxygen for complete conversion.Fig.9shows that the presence of 10,000ppm H 2causes outstanding NO x conversion.Contrary,in the study withC 3H 6significant deNO x appears between 160and 3208C only with a peak conversion of ca.80%corresponding to a N 2selectivity of 45%.A minor deNO x activity is obtained with CO being in line with the results demonstrated in Section 3.3.1.As discussed there,the inhibition of deNO x is related to the blocking of active Pt sites by C 3H 6and CO suppressing substantial dissociation of NO [29].This effect is obviously stronger for CO,whereas it has to be taken into account that much more CO molecules are dosed as compared to C 3H 6.Additionally,Fig.9demonstrates that C 3H 6and CO mainly react with O 2,particularly above 3008C.Finally,from the present experiments it is concluded that among the tested reductants only H 2shows efficient NO x reduction on 0.3Pt/11W/ZrO 2.Fig.9.Effect of H 2,C 3H 6and CO on the deNO x performance of 0.3Pt/11W/ZrO 2(X (NO x )—,S (N 2)--,S (N 2O),X (C 3H 6)—,X (CO)—),The concentration of reducing agent 10,000ppm H 2,1000ppm C 3H 6or 9000ppm CO;remaining conditions are the same as described in Fig.5.Fig.8.Effect of CO on the H 2-deNO x performance of 0.3Pt/11W/ZrO 2(X (NO x )—,S (N 2)--,S (N 2O),X (CO)—).Conditions:m =1.50g,c (NO)=500ppm,c (CO)=400ppm,c (H 2)=2000ppm,c (O 2)=6.0vol.%,Ar balance,F =500ml min À1(STP),S.V.=22.000h À1,b =1.0K min À1.F.J.P.Schott et al./Applied Catalysis B:Environmental 87(2009)18–2923。

润滑油荧光光谱标准物质英文回答：Fluorescence spectroscopy is a powerful technique used in various fields, including the analysis of lubricating oils. Standard reference materials for fluorescence spectroscopy of lubricating oils are essential for ensuring accurate and reliable measurements.One example of a standard reference material for lubricating oil fluorescence spectroscopy is a set of calibrated oil samples with known fluorescence properties. These samples can be used to calibrate fluorescence spectrometers and validate the accuracy of measurements. By comparing the fluorescence signals of unknown oil samples with those of the reference materials, the composition and quality of the lubricating oil can be determined.Another example of a standard reference material is a set of fluorescent dyes or compounds that mimic thefluorescence properties of lubricating oils. These dyes can be added to the oil samples to create a standardized fluorescence response. By measuring the fluorescence intensity of the dye-lubricating oil mixture, the concentration of the dye can be determined, which can then be used to calculate the concentration of specific components in the lubricating oil.Standard reference materials for lubricating oil fluorescence spectroscopy are crucial for quality control and ensuring consistency in measurements across different laboratories. They enable accurate and reliable analysis of lubricating oils, which is vital for maintaining the performance and longevity of machinery and equipment.中文回答：润滑油荧光光谱标准物质是确保测量准确性和可靠性的重要工具。

Part B: Test Methods Section, Method C-07DETERMINATION OF TOTAL MERCURY IN SURFACE COATING M ATERIALSAND APPLIED COATINGS 351SCOPE1.1This m ethod describes a general procedure for the determ ination of the total mercurycontent in surface coating materials and applied coatings, as applicable to item 9(d) ofPart I of Schedule I to the Hazardous Products Act and the Surface Coating MaterialsRegulation (SOR 2005).2APPLICABLE DOCUMENTS2.1M. Lanouette, “Determination of Total Mercury in Paints and Applied Coatings by directanalysis without any wet chemistry pretreatment steps using a Mercury Analyzer. MethodDevelopment.” Project # 2001-06232.2EPA Method 7473 Mercury in solids and solutions by Thermal Decom position,Am algam ation, and Atomic Absorption Spectrophotom etry.2.3AOAC O fficial Methods of Analysis, 14th Edition, Sections 25.131 - 25.145 (1984).2.4ASTM Standard Test Method D3624 - 85a.2.5W.R. Hatch and W.L. Ott, Determination of Sub-Microgram Quantities of Mercury byAtom ic Absorption Spectrophotom etry, Anal. Chem., Vol.40, No.14, p 2085 (1968).2.6 B. Marchand, “Determination of leachable cadmium, barium, antimony, selenium andarsenic in decorative or protective coatings” Project #2000-0596, 2001-01-24.2.7 B. Séguin, M. Charette “Determination of Total Mercury in Paints and Applied Coatings”Project #2002-06982.8M. Charette, “Determination of Total Mercury in Surface Coating Materials and AppliedCoatings” Project #2005-0882.2.9W orking Instructions for Leco AMA254 Mercury Analyzer, S34 (2006)2.10Instruction Manual for AMA254 Advanced Mercury Analyzer, LECO Corporation3REAGENTS AND APPARATUS3.1Acetone (HPLC grade, Fisher Scientific) 13.2Tetrahydrofuran (HPLC grade, Fisher Scientific) 13.3Muffle Furnace. (0-1100/C)3.4NIST 1633b,U.S. Department of Com merce, National Institute of Standards andTechnology. Certified value (see Certificate of Analysis)Standard used for low-level calibration curve.3.5NIST 2709, U.S. Department of Com merce, National Institute of Standards andTechnology. Certified value (see Certificate of Analysis)Standard used for high-level calibration curve.3.6NIST 2582, U.S. Department of Com merce, National Institute of Standards andTechnology. No Certified value for MercuryStandard used for daily verification of high-level calibration curve.3.7NIST 2685b, U.S. Department of Com merce, National Institute of Standards andTechnology. Certified value (see Certificate of Analysis)Standard used for daily verification of low-level calibration curve.1Where applicable, suitable equivalent reagents and materials may be used.Part B: Test Methods Section, Method C-07DETERMINATION OF TOTAL MERCURY IN SURFACE COATING M ATERIALSAND APPLIED COATINGS 353.8Advanced Mercury Analyzer AMA254, LECO C orporation.3.9AS254 Solid Sample Autoloader for small or large nickel sample boats.3.10Desiccator.3.11Scalpel or other suitable stainless steel blade tool.3.12Nickel boat.3.13Air convection oven.3.14Analytical balance4EXPERIMENTAL PROCEDURE4.1Preparation of equipment4.1.1W ash the supplies for measurement, i.e., sample boats, tweezers, spatulas andsteel blades with distilled water in an ultrasonic bath for at least 20 minutes.4.1.2Rinse with Millipore deionized water.4.1.3Bake the supplies for m easurem ent in the muffle furnace for at least 1 hour at300°C prior to analysis.4.1.4Cover supplies for m easurem ent with aluminum foil once they are bak ed toprevent possible contam ination from laboratory dust.4.2For liquid paints:4.2.1Mix the sam ple thoroughly for at least 5 minutes.4.2.2Apply liquid paint on a glass plate with a foam paint brush or other suitableapplicator.4.2.3Dry the sample in the convection air oven at 60°C for at least 1hour.4.2.4Scrape off the applied coating from the plate with a scalpel or other suitablestainless steel blade.4.2.5Transfer the recovered coating in a weighing vessel and dry to constant mass(±2%) in an air convection oven at 60°C for at least 1 hour.4.2.6Rem ove the vessel from the oven and cool to ambient temperature in adesiccator.4.2.7Transfer about 50 mg of the dried coating into a sample boat and weigh to thenearest 1 mg.4.3For applied coatings:4.3.1Scrape off the applied coating from the article under test with a scalpel or othersuitable stainless steel blade, being careful not to remove any of the underlyingsubstrate m aterial.4.3.2Place the removed coating in a weighing vessel4.3.3Dry the sample to constant mass (±2%) in an air convection oven at 60°C for atleast 1 hour.4.3.4Rem ove the vessel from the oven and cool to ambient temperature in adesiccator.4.3.5Transfer about 50 m g of the dried coating into a sam ple boat and weigh to thenearest 1 mg.Part B: Test Methods Section, Method C-07DETERMINATION OF TOTAL MERCURY IN SURFACE COATING M ATERIALSAND APPLIED COATINGS 35 Alternatively, remove the coating with a suitable solvent2, and collect into a weighing vessel.Evaporate the solvent from the removed coating, then dry in an air convection oven at 60°C for at least 1 hour. Resume from step 4.3.44.4For control samples:4.4.1Do not dry the standard reference material (NIST 1633b, NIST 2685b) asindicated on the certificate of analysis.4.4.2Transfer about 75 mg of the SRM 1633b and about 50 mg of 2685b into sam pleboats and weight to the nearest 1 mg.4.4.3Paint control NIST 2582 (High level calibration curve check)4.4.3.1Dry to constant mass (± 2%) in an air convection oven at 60°C for at least1 hour.4.4.3.2Rem ove the vessel from the oven and cool to ambient temperature in adesiccator.4.4.3.3Accurately transfer 8 to 10 (<10m g) of the dried control into a sam pleboat and weigh to the nearest 1 mg5CALIBRATION5.1Calibration curveThe calibration of the instrument is done annually. In addition, the calibration is performedeach time the catalytic tube is replaced.Prepare a calibration curve by weighing into a sample boat to the nearest 1 mg intriplicate the approximate m ass of the standard according to the following table.2THF m ay be used to facilitate the rem oval of the applied coating. T hese solvents, however, should not be used if the test article's substrate material is a plastic.3These concentration may vary with the concentration value rep orted on the certificate of analysis from NIST.Part B: Test Methods Section, Method C-07DETERMINATION OF TOTAL MERCURY IN SURFACE COATING M ATERIALSAND APPLIED COATINGS 355.2Daily verification of calibration curve5.2.1For low level mercury:- W eigh standard #3 in triplicate- Test the standard as a regular sample not as a standard.- Verify that the standards must be measured within 10% of their certified valuesfor the curve to be considered valid.5.2.3The results of the daily verification are added to the control chart and should thetest result be outside the warning limits, the quality control procedure should beenforced as per section 8.2.1.6DETERMINATION6.1Use m ethod Mercury Analysis from the LECO software according to the W orkingInstructions for the instrument with the following parameters:6.2Analysis of blanks6.2.1Leave empty (no sample boat) the first and the last sample location on theautosampler for each run to verify any contamination in the system.6.2.2Install one clean em pty boat on the autosam pler after the first em pty sam plelocation and before the last empty sample location. Results should indicate lessthan 5 ppb of Hg.6.3Analysis of samplesAnalyse each sample in triplicate whenever applicable. If necessary, take a smaller testsample in order to ensure that the absorbance measurement is taken within theinstrument's linear dynamic range (low cell peak must be #0.8).6.4Analysis of controlAnalyse certified material (NIST 2685b for low concentration or NIST 2582 for highconcentration) after nine analyses are completed (3 sam ples).Part B: Test Methods Section, Method C-07DETERMINATION OF TOTAL MERCURY IN SURFACE COATING M ATERIALSAND APPLIED COATINGS 354The standard deviation (s) of the test results may be calculated according to the following equation, where:x i is the result of each individual determination, x ) is the average of the replicate determinations and n is the total number of replicates.7REPORTING7.1The concentration of mercury in the sample is calculated by the Mercury Analyzer LECO software and reported as ppb on the instrument printout. The results are modified to bepresented in mg/kg by dividing by 1000.7.2W here applicable, the average (x.x) of replicate determinations and the standard deviation(s) of replicate determinations (s for n > 2) will be calculated 4, and the result of analysisreported in the following form at:7.3W henever mercury is not detected, the result shall be reported as less than the limit ofquantitation as presented in Section 11.8QUALITY CONTROL PROCEDURE 8.1In order to ensure the proper operation of the available instrumentation and that theprecision and accuracy of the analytical measurem ents meet the specifications of themethod, the following quality control procedures shall be conducted concurrently with theanalysis of the test sample.8.2The normal and correct operation of the Mercury Analyzer apparatus shall be verifiedaccording to the following guidelines:8.2.1Record the concentration of the control (NIST 2685 and NIST 2582) in theanalytical instrument's QC logbook. Verify that the measurement is within thewarning limits (±2×s) and does not exceed the control limits (±3×s). If this controlmeasurement falls within control lim its, a note shall be entered in the test sam plefile to the effect that the instrument calibration was found to be "within control".Should the test results be outside of the lim its, the entire analytical procedure shallbe repeated. Should the instrument be found in a state of disrepair or out ofcalibration, the Mercury Analyzer shall imm ediately be repaired and/or re-calibratedto meet the prescribed operating conditions prior to proceeding with the analysis.Part B: Test Methods Section, Method C-07DETERMINATION OF TOTAL MERCURY IN SURFACE COATING M ATERIALSAND APPLIED COATINGS 359PRECISION AND BIAS9.1RepeatabilityThe deviation between replicate test results, as obtained on N IST 1633b standardreference material by the same analyst with the same instrument under constant operatingconditions, should, in the normal and correct operation of the test method, not differ morethan 6.67% (2.8 × %CV) rep eatability limit at a 95% probability level.9.2ReproducibilityThe difference between two independent test results, as obtained by different analystsworking in two different laboratories on identical test material, should, in the normal andcorrect operation of the test method, not differ more than 11.79 (2.8 × %CV)reproducibility lim it at a 95% probability level.9.3BiasThere is no bias observed for the analysis of the standard reference m aterial.10LIMIT OF DETECTIONThe limit of detection (LOD) of this method, as determine by Mercury Analyzer, has beencalculated to be 2.6 × 10-2 mg/kg Hg. (2 × 1.645 × s)11LIMIT OF QUANTITATIONThe limit of quantitation (LOQ) of this method, as determined by Mercury Analyzer, has beencalculated to be 7.8 × 10-2 mg/kg Hg. All results below LOQ should be reported as < 7.8 × 10-2mg/kg Hg.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . END . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .。

a r X i v :a s t r o -p h /0411032v 1 1 N o v 2004Mon.Not.R.Astron.Soc.000,1–7(2004)Printed 2February 2008(MN L A T E X style file v2.2)The absorption spectrum of V838Mon in 2002February -March.I.Atmospheric parameters and iron abundance.⋆Bogdan M.Kaminsky 1†,Yakiv V.Pavlenko 1‡1Main Astronomical Observatory of Ukrainian Academy of Sciences,Golosiiv woods,03680Kyiv-127,UkraineReceived ;acceptedABSTRACTWe present a determination of the effective temperatures,iron abundances,and mi-croturbulent velocities for the pseudophotosphere of V838Mon on 2002February 25,and March 2and 26.Physical parameters of the line forming region were obtained in the framework of a self-consistent approach,using fits of synthetic spectra to observed spectra in the wavelength range 5500-6700˚A .We obtained T eff=5330±300K,5540±270K and 4960±190K,for February 25,March 2,and March 26,respectively.The iron abundance log N (Fe)=−4.7does not appear to change in the atmosphere of V838Mon from February 25to March 26,2002.Key words:stars:atmospheres –stars:abundances –stars:individual:V838Mon1INTRODUCTIONThe peculiar variable star V838Mon was discovered during an outburst in the beginning of 2002January (Brown 2002).Two further outbursts were then observed in 2002February (Munari et al.2002a;Kimeswenger et al.2002;Crause et al.2003)and in general the optical brightness in V-band of the star increased by 9mag.Since 2002March,a gradual fall in V-magnitude began which,by 2003January,was re-duced by 8mag.The suspected progenitor of V838Mon was identified by Munari et al.(2002a)as a 15mag F-star on the main sequence.Possibly V838Mon might have a B3V companion (Desidera &Munari 2002),but it could be a background star.The discovery of a light echo (Henden et al.2002)allowed an estimate of the distance to V838Mon and,according to recent works based on HST data (Bond et al.2003;Tylenda 2004)its distance is 5-6kpc.If these estimations are correct,at the time of maximum brightness V838Mon was the most luminous star in our Galaxy.Details of the spectral evolution of the star are described in Kolev et al.2002;Wisniewski et al.2003;Osiwala et al.2002).During outbursts (except for the last)the spec-trum displayed numerous emission lines with P Cyg pro-files,formed in the expanding shell and around an F-or A-star (Kolev et al.2002).On the other hand,absorption spectra appropriate to a red giant or supergiant were ob-served in quiescent periods.Strong lines of hydrogen,D lines of sodium,triplets of calcium and other elements show P⋆Based in part on observations collected with the 1.83m tele-scope of the Astronomical Observatory in Asiago,Italy †E-mail:bogdan@mao.kiev.ua ‡E-mail:yp@mao.kiev.uaCyg profiles.They have similar profiles and velocities vary-ing from −500km s −1in late January to −280km s −1in late March (Munari et al.2002a).Since the middle of 2002March,the emissions are considerably weakened and the spectrum of V838Mon evolved to later spectral classes.In middle of 2002April,there were present some lines of TiO;in May the spectrum evolved to the“very cold”M-giant (Banerjee &Ashok 2002).In October Evans et al.(2003)characterized it as a L-supergiant.Recently Kipper et al.(2004)found for iron group ele-ments [m/H]=−0.4,while abundances of lithium and some s-process elements are clearly enhanced.This results was obtain using the static LTE model.These results are very dependent on the model atmo-sphere and spectrum synthesis assumptions.The nature of the outbursts remains a mystery.Possible explanations include various thermonuclear processes (very slow nova,flare post-AGB),and the collision of two stars (Soker &Tylenda 2003).Munari et al.(2002a)suggested that V838Mon is a new type of a variable star,because comparison with the closely analogous V4334Sgr and M31RV has shown significant enough differences in the observed parameters.In this paper we discuss the results of the determina-tion of iron abundance and atmospheric parameters of V838Mon.These we obtained from an analysis of absorption spec-tra of V838Mon on 2002February 25and March 2and 26.The complexity and uniqueness of the observed character-istics of V838Mon practically excluded a definition of the parameters of the atmosphere using conventional methods,based on calibration on photometric indices,ionization bal-ance,profiles of hydrogen lines.Indeed,the presence around the star of a dust shell,and the uncertain determination of2Bogdan M.Kaminsky,Yakiv V.Pavlenko interstellar reddening(from E B−V=−0.25to E B−V=−0.8 Munari et al.2002a),affects the U−B and B−V colours. Emission in the hydrogen lines provides severe problems for their application in the estimation of effective temperature. Moreover,both the macroturbulent motions and expansion of the pseudophotosphere merges the numerous lines in wide blends.As a result,a single unblended line in the spectrum of V838Mon cannot be found at all,and any analysis based on measurements of equivalent widths is completely excluded.The observational data used in this paper are described in section2.Section3explains some background to our work and some details of the procedure used.We attempt to de-termine T eff,the microturbulent velocity V t and the iron abundance log N(Fe)in the atmosphere of V838Mon in theframework of the self-consistent approach in section4.Some results are discussed in section5.2OBSER V ATIONSSpectra of V838Mon were obtained on2002February25 and March26with the Echelle+CCD spectrograph on the 1.82m telescope operated by Osservatorio Astronomico di Padova on Mount Ekar(Asiago),and freely available to the community from http://ulisse.pd.astro.it/V838Mon/.A 2arcsec slit was used withfixed E-W orientation,produc-ing a PSF with a FWHM of1.75pixels,corresponding to a resolving power close to20000.The detector was a UV coated Thompson CCD1024×1024pixel,19micron square size,covering in one exposure the wavelength range4500to 9480˚A(echelle orders#49to#24).The short wavelength limit is set by a2mm OG455long-passfilter,inserted in the optical train to cut the second order from the cross-disperser. The wavelength range is covered without gaps between ad-jacent echelle orders up to7300˚A.The spectra have been extracted and calibrated using IRAF software running un-der Linux operating system.The spectra are sky-subtracted andflat-fielded.The wavelength solution was derived simul-taneously for all26echelle orders,with an average r.m.s of 0.18km s−1.The8480-8750˚A wavelength range of these Asi-ago spectra has been described in Munari et al.(2002a,b).Another set of spectra(R∼32000)for March2was obtained with the echellefibre-fed spectrograph on the1.9-m SAAO telescope kindly provided for us by Dr.Lisa Crause (see Crause et al.2003for details).3PROCEDURETo carry out our analysis of V838Mon we used the spectral synthesis techniques.Our synthetic spectra were computed in the framework of the classical approach:LTE,plane-parallel media,no sinks and sources of energy inside the atmosphere,and transfer of energy provided by the radia-tionfield and by convection.Strictly speaking,none of these assumptions is100% valid in atmosphere of V838Mon.Clearly we have non-static atmosphere which may well have shock waves mov-ing trough it.Still we assumed that in any moment the structure of model atmosphere of V838Mon is similar to model atmospheres of supergiants.Indeed,temporal changes of the absorption spectra on the days were rather marginal.0.00050.0010.00150.0020.00250.0030.00350.004-200-150-100-50 0 50 100 150 200Velocity (km s-1)V exp=160 km s-1V*sin i=80 km s-1V macro=50 km s-1parison of expansion(V exp=160km s−1),rota-tional(v∗sin i=80km s−1)and macroturbulent(V macro=50 km s−1)profiles used in this paper to convolve synthetic spectra.Most probably,for this object,we see only a pseudophoto-sphere,which is the outermost part of an expanding enve-lope.Therefore,ourfirst goal was to determine whether it is possible tofit our synthetic spectra to the observed V838 Mon spectra.At the time of the observations the spectral class of V838Mon was determined as K-type(Kolev et al.2002). Absorption lines in spectrum of V838Mon form compara-tively broad blends.Generally speaking,there may be a number of broad-ening mechanisms:•Microturbulence,which is formed by small scale(i.e τ≪1)motions in the atmosphere.In the case of a super-giant,V t usualy does not exceed10km s−1.In our analysis we determined V t from a comparison of observed and com-puted spectra.•Stellar rotation.Our analysis shows that,in the case of V838,we should adopt v∗sin i=80km s−1tofit the observed spectra.This value is too high for the later stages of stellar evolution,for obvious reasons.In reality rotation cannot contribute much to the broadening of lines observed in spectra of most supergiants.•Expansion of the pseudophotosphere of the star.Asym-metrical profiles of expansion broadening can be described, to afirst approximation,by the formulaG(v,λ,∆λ)=const∗∆λThe absorption spectrum of V838Mon3−0.50.511.522.5566056705680569057005710N o r m a l i s e d F l u xWavelength (Å)February 3February 25March 2March 26Figure 2.Spectra of V838Mon observed on February 3,Febru-ary 25,March 2and March 262002emission:many lines are observed in emission.This demon-strates that effects of the radial expansion of the line-forming layers were not significant for the dates of our data and for-mally obtained value V exp =160km s −1is not real.•Macroturbulence.After the large increase of luminos-ity in 2002January-February,large scale (i.e.of magnitude τ>1)macroturbulent motions should be very common in the disturbed atmosphere of V838Mon.Our numerical ex-periments showed that,to get appropriate fits to the ob-served spectra taking into account only macroturbulent ve-locities,we should adopt V macro ∼50km s −1.In any case,for the times of our observations the spectra of V838Mon resemble the spectra of “conventional”super-giants.Our V838Mon spectra for February 25,March 2and 26agree,at least qualitatively,with the spectrum of Arcturus (K2III),convolved with macroturbulent velocity profile,given by a gaussian of half-width V macro =50km s −1(Fig.3).The observed emissions in the cores of the strongest lines are formed far outside,perhaps at the outer boundary of the expanding envelope,i.e.in the region which is heated by shock wave dissipation.As result of our first numerical experiments,we con-cluded that the spectra of V838Mon in 2002February -March were similar to the spectrum of a normal late (su-per)giant,broadened by strong macroturbulence motions and/or expansion of its pseudophotosphere.Unfortunately we cannot,from the observed spectra,distinguish between broadening due to the macroturbulence and expansion (see next section).It is worth noting that the observed spectra of V838Mon are formed in a medium with decreasing temperature to the outside,i.e.in the local co-moving system of co-ordinates the atmosphere,to a first approximation,can be described by a “normal”model,at least in the region of formation of weak or intermediate strength atomic lines.0.10.20.3 0.4 0.5 0.6 0.7 0.8 0.91 1.1 570057105720573057405750N o r m a l i s e d F l u xWavelength (Å)V 838 Mon ArcturusArcturus conv. V macro =50 km s −1Figure parison of the spectrum of V838Mon and that of Arcturus,convolved with macroturbulent profile V macro =50km s −13.1Fits to observed spectraWe computed a sample of LTE synthetic spectra for a grid of Kurucz (1993)model atmospheres with T eff=4000–6000K using the WITA612program (Pavlenko 1997).Synthetic spectra were computed with wavelength step 0.02˚A ,micro-turbulent velocities 2–18km s −1with a step 1km s −1,iron abundances log N (Fe)=−5.6→−3.6dex 1,with a step 0.1dex.Then,due to the high luminosity of the star,we formally adopt log g =0.Synthetic spectra were computed using the VALD (Kupka et al.1999)line list.For atomic lines the line broadening constants were taken from VALD or computed following Unsold (1955).For the dates of our observations lines of neutral iron dominate in the spectra.Fortunately,they show rather weak gravity/pressure dependence,therefore the uncertainty in the choice of log g will not be important in determining our main results;the dependence of the computed spectra on T effis more significant (see Fig.4).The computed syn-thetic spectra were convolved with different profiles,and then fitted to the observed spectra following the numeri-cal scheme described in Jones et al.(2002)and Pavlenko &Jones (2002).In order to determine the best fit parameters,we com-pared the observed residual fluxes r obsλwith computed values H theorλ+f s .We let H obs λ= F theor x −y ∗G (y )∗dy ,where F theor λis the theoretical flux and G (y )is the broadening profile.In our case G (y )may be wavelength dependent.To get the best fit we find the minima per point of the 2D functionS (f s ,f g )=Σ(1−H synt /H obs )2.We calculated these minimization parameters for our grid of synthetic spectra to determine a set of parameters f s (wavelength shift parameter)and f g (convolution parame-ter).The theoretical spectra were convolved with a gaussian profile.Our convolution profile is formed by both expan-sion and macroturbulent motions.We cannot distinguish between them in our spectra.To get a numerical estimate1in the paper we use the abundance scaleN i =14Bogdan M.Kaminsky,Yakiv V.Pavlenko0.60.650.7 0.75 0.8 0.85 0.90.95 1 6306 6308 6310 6312 6314 6316 6318 6320 6322 6324N o r m a l i s e d F l u xWavelength (Å)T eff =4000 KT eff =5000 K logg=0T eff =5000 K logg=1T eff =6000 KFigure 4.Dependence of computed spectra on T effand log gof the broadening processes in the pseudophotosphere,we use a formal parameter V g ,which describes the cumulative effect of broadening/expansion motions.The parameters f s and f g were determined by the min-imization procedure;the procedure was carried out for dif-ferent spectral regions.We selected for analysis 6spectral orders in the interval 5600-6700˚A .In the red,spectral lines are blended by telluric spectra,and are of lower S/N.In the blue the blending of the spectra are rather high.Our main intention was to obtain a self-consistent solution sep-arately for different echelle orders,and then compare them.If we could obtain similar parameters from different spec-tral regions it can be evidence of the reality of the obtained solution.4RESULTS 4.1The SunTo be confident in our procedure,we carried out a similar analysis for the Sun.For this case we know the solar abun-dances and other basic parameters,therefore our analysis provides an independent estimation of the quality of our procedure:•From the solar atlas of Kurucz et al (1984)we ex-tract spectral regions corresponding to our observed orders of V838Mon;•we convolve the solar spectra with a gaussian of V macro =50km s −1.•we carried out a spectral analysis of the spectral regions with our procedure;again,model atmospheres from Kurucz (1993)with a grid of different log g ,T eff,log N (Fe)were used.The results of our “re-determination”of parameters of the solar atmosphere are given in Table 1.The best fit to one spectral region is shown in Fig.5.From our analysis of the solar spectrum we obtained T eff=5625±125K,log N (Fe)=−4.48±0.15dex,V t =1.2±0.4km s −1.Here and below we used the standard deviation for error esti-mates.All these parameters are in good agreement with theTable 1.Parameters of the solar atmosphere116480–668555001-4.545.8126300–649057502-4.646.4136125–631557501-4.442.9145960–614557501-4.244.1165660–581055001-4.643.9175520–567055001-4.642.9Averaged56251.2-4.4844.3The absorption spectrum of V838Mon5–For February25we obtained T eff=5330±300K,log N(Fe)=−4.7±0.14dex and V t=13.±2.8km s−1.–For the March26data the mean values are T eff=4960±270K,log N(Fe)=−4.68±0.11dex,V t=12.5±1.7km s−1.–And for March2the mean values are T eff=5540±190K,log N(Fe)=−4.75±0.14dex,V t=13.3±3.2kms−1.–We obtained V g=54±3,47±3and42±5km s−1for February25,March2and March26,respectively.–The f s parameter provides the heliocentric velocity ofV838Mon.We obtained V radial=−76±3,−70±3and−65±3km s−1for February25,March2and March26,respectively.Most probably,we see some reduction in theexpansion velocity of the envelope.5DISCUSSIONFrom a comparison of our results for all three dates we see that:•The effective temperature for March26is somewhat lower then for the previous dates.This is an expected re-sult,in view of the gradual cooling of envelope.However, for March2we found a slightly higher value of temperature than for February25.A possible explanation is the heating of the pseudophotosphere as result of the third outburst.•The microturbulent velocities are very similar and ex-tremely high for all three dates.•Our analysis shows a lower value of V g for the later dates:the effects of expansion and macroturbulence were weakened at the later stages of evolution of the pseudopho-tosphere of V838Mon.•The iron abundances log N(Fe)=-4.7±0.14are similar for all dates.Our estimates of effective temperature are in a good agreement with Kipper et al.(2004),although we used dif-ferent procedures of analysis.The iron abundance([Fe/H]=−0.4)and microturbulent velocity(V t=12km s−1)found by Kipper et al.(2004)for March18are in agreement with our results.Our deduced“effective temperatures”as well as those in Kipper et al(2004)do not correspond with values ob-tained from photometry(T eff∼4200K).We assume that in our analysis we deal with temperatures in the line forming region,rather than with the temperatures at photospheric levels which determine the spectral energy distribution of V838Mon and the photometric indices.Indeed,the formally determined microturbulent velocity V t=13km s−1exceeds the sound velocity in the atmosphere(4-5km s−1).This means that the region of formation of atomic lines should be heated by dissipation of supersonic motions:the temper-ature there should be higher than that given in a plane-parallel atmosphere of T eff∼4200K.Certainly the effect cannot be explained by sphericity effects:the temperature gradients in the extended atmo-spheres should be steeper(see Mihalas1978),therefore tem-peratures in the line forming regions should be even lower, in contradiction with our results.Strong deviations from LTE are known to occur during the photospheric stages of the evolution of novae and super-0.40.50.60.70.80.911.16480 6500 6520 6540 6560 6580 6600 6620 6640 6660 6680 6700 NormalisedFluxWavelength (Å)V 838 MonT eff=5250 KT eff=4500 K0.40.50.60.70.80.911.16300 6320 6340 6360 6380 6400 6420 6440 6460 6480 6500 NormalisedFluxWavelength (Å)V 838 MonT eff=5000 KT eff=4500 K0.40.50.60.70.80.911.16120 6140 6160 6180 6200 6220 6240 6260 6280 6300 6320 NormalisedFluxWavelength (Å)V 838 MonT eff=5250 KT eff=4500 KFigure6.The bestfits of synthetic spectra to11-13orders of the observed spectrum of V838Mon on February25,found by the minimization procedure.novae.The main effect there should be caused by deviations from LTE in the ionization balance.However,in our case we used lines of the neutral iron,which dominate by number. We cannot expect a reduction in the density of Fe I atoms in the comparatively cool atmosphere of the star.Further-more,we exclude from our analysis strong lines with P Cyg profiles.Lines of interest in our study have normal profiles.6Bogdan M.Kaminsky,Yakiv V.PavlenkoTable2.Atmospheric parameters for V838MonAsiago spectraFebruary25116480–6685525015-4.753.2-79.6126300–6490500014-4.954.5-76.3136125–6315525010-4.756.0-82.7145960–6145575017-4.552.5-79.5165660–581050009-4.960.7-67.1175520–5670575014-4.751.1-73.6Averaged533013.2-4.7354.7-76.5March26116480–6685475012-4.843.7-67.3126300–6490475014-4.844.7-68.3136125–6315475010-4.546.0-74.3145960–6145500015-4.842.1-65.8165660–5810500011-4.738.8-52.2175520–5670550013-4.539.7-63.6Average496012.5-4.6842.5-65.2SAAO spectraMarch2116480–6685550012-4.645.3-80.6126300–6490525016-4.955.8-77.3136125–631552507-4.642.8-78.9145960–6145575014-4.849.0-80.6165660–5810550015-4.951.7-68.1175520–5670600016-4.742.1-80.0Average554013.3-4.7547.8-77.6The absorption spectrum of V838Mon70.40.50.6 0.7 0.8 0.9 1 1.1 5960 5980 6000 6020 6040 6060 6080 6100 6120 6140 6160N o r m a l i s e d F l u xWavelength (Å)V 838 Mon T eff =5750 K T eff =4500 K0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 5660 5680570057205740576057805800N o r m a l i s e d F l u xWavelength (Å)V 838 Mon T eff =5000 K T eff =4500 K0.40.50.6 0.7 0.8 0.9 1 1.1 5500 5520 5540 5560 5580 5600 5620 5640 5660 5680N o r m a l i s e d F l u xWavelength (Å)V 838 Mon T eff =5750 K T eff =4500 K Figure 7.The best fits of synthetic spectra to orders 14,16and 17of the observed spectrum of V838Mon on February 25,found by the minimization procedure.•most probably,the line-forming region is heated by su-personic motions –our spectroscopic temperatures exceed photometrically determined T effby ∼1000K;•we do not find any significant change in the iron abun-dance in atmosphere V838from February 25to March 26.•we derived a moderate deficit of iron log N (Fe)∼−4.7in the atmosphere of V838Mon.ACKNOWLEDGMENTSWe thank Drs.Ulisse Munari,Lisa Crause,Tonu Kipper and Valentina Klochkova for providing spectra and for discus-sions of our results.We thank Dr.Nye Evans for improving text of paper.We thank unknown referee for many helpful remarks.This work was partially supported by a PPARC visitors grants from PPARC and the Royal Society.YPs studies are partially supported by a Small Research Grant from American Astronomical Society.This research has made use of the SIMBAD database,operated at CDS,Strasbourg,France.REFERENCESAllen C.W.,1973,Astrophysical quantities,3rd edition,TheAthlone Press,LondonBanerjee D.P.K.,Ashok N.M.,2002,A&A,395,161Bond H.E.,et al.,2003,Natur,422,405Brown N.J.,2002,IAU Circ,7785,1Crause L.A.,Lawson W.A.,Kilkenny D.,van Wyk F.,MarangF.,Jones A.F.,2003,MNRAS,341,785Desidera,S.,Munari,U.,2002,IAU Circ,7982,1Evans A.,Geballe T.R.,Rushton M.T.,Smalley B.,van LoonJ.Th.,Eyres S.P.S.,Tyne V.H.,2003,MNRAS,343,1054Henden A.,Munari U.,Schwartz M.B.,2002,IAU Circ,7859Jones H.R.A.,Pavlenko Ya.,Viti S.,Tennyson J.,2002,MNRAS,330,675JKimeswenger S.,Ledercle C.,Schmeja S.,Armsdorfer B.,2002,MNRAS,336,L43Kipper T.,et al.,2004,A&A,416,1107Kolev D.,Mikolajewski M.,Tomow T.,Iliev I.,Osiwala J.,Nirski J.,Galan C.,2002,Collected Papers,Physics (Shu-men,Bulgaria:Shumen University Press),147Kupka F.,Piskunov N.,Ryabchikova T.A.,Stempels H.C.,WeissW.W.,1999,A&AS,138,119Kurucz R.L.,Furenlid I.,Brault J.,Testerman L.,1984,Nationalsolar obs.-Sunspot,New Mexico Kurucz R.L.,1993,CD-ROM 13Mihalas D.,1978,Stellar atmospheres,Freeman &Co.Munari U.,et al.,2002a,A&A,389,L51Munari U.,Henden A.,Corradi R.M.L,Zwitter T.,2002b,in”Classical Nova Explosions”,M.Hernanz and J.Jos´e eds.,AIP Conf.Ser.637,52Osiwala J.P.,Mikolajewski M.,Tomow T.,Galan C.,Nirski J.,2003,ASP Conf.Ser.,303,in pressPavlenko Y.V.,1997,Astron.Reps,41,537Pavlenko Ya.V.,Jones H.R.A.,2002.A&A,397,967Pavlenko Ya.V.,2003.Astron.Reps,47,59Soker N.,Tylenda R.,2003,ApJ,582,L105Tylenda R.,2004,A&A,414,223Unsold A.,1955Physik der Sternatmospheren,2nd ed.Springer.BerlinWisniewski J.P.,Morrison N.D.,Bjorkman K.S.,MiroshnichenkoA.S.,Gault A.C.,Hoffman J.L.,Meade M.R.,Nett J.M.,2003,ApJ,588,486This paper has been typeset from a T E X/L A T E X file preparedby the author.。