Nonlinear absorption properties of ?axial-bonding ?type tin(IV)
tetratolylporphyrin based hybrid porphyrin arrays
P.Prem Kiran a ,D.Raghunath Reddy b ,Bhaskar G.Maiya b ,Aditya K.Dharmadhikari c ,G.Ravindra Kumar c ,D.Narayana Rao
a,*
a
School of Physics,University of Hyderabad,Hyderabad 500046,India b
School of Chemistry,University of Hyderabad,Hyderabad 500046,India c
Tata Institute of Fundamental Research,Colaba,Mumbai 400005,India
Received 10September 2004;received in revised form 14March 2005;accepted 5April 2005
Abstract
The nonlinear absorption properties of ?axial-bonding ?type hybrid porphyrin arrays based on a tin(IV)tetra-tolylporphyrin (SnTTP)sca?old are studied with picosecond and nanosecond pulses.The e?ect of di?erent central metal atoms substituted adjacent to the tin(IV)porphyrin in the oligomer structure is discussed.In the picosecond regime the lifetimes of the excited singlet states and two-photon absorption (TPA)processes dominate leading to inter-esting switching of nonlinear absorption behaviour.The TPA cross-section (r TPA )is found to be as high as 396·10à46cm 4s photon à1molecule à1,for an oligomer with Sn and Ni porphyrin macrocycles.However,in the nano-second regime the optical limiting performance has increased considerably with increasing number of porphyrins in the array and excited state absorption is found to play a major role.ó2005Elsevier B.V.All rights reserved.
PACS:42.65.àk;42.65.Re;42.79.àe
Keywords:Nonlinear optics;Ultrafast processes;Optical limiting
1.Introduction
Nonlinear absorption is a phenomenon de?ned as an increase or decrease in the absorption coe?-cient with increasing intensity.The former re-sponse is called as reverse saturation of absorption (RSA),while the latter is known as sat-uration of absorption (SA).Organic materials with delocalized electrons are of great importance be-cause of their large nonlinear optical absorption coe?cients,architectural ?exibility,and ease of
0030-4018/$-see front matter ó2005Elsevier B.V.All rights reserved.doi:10.1016/j.optcom.2005.04.008
*
Corresponding author.Tel./fax:+9104023011230.E-mail address:dnrsp@uohyd.ernet.in (D.N.
Rao).
Optics Communications 252(2005)
150–161
fabrication.Recently materials showing RSA behaviour have been in focus for optical limiting applications[1].SA in various materials has been studied for applications in laser pulse compression and laser ampli?cation[2,3].An intense laser pulse redistributes the molecular population between the ground and excited states causing a transient mod-i?cation in the optical properties of the material. The dependence of transmission of organic mole-cules on light intensity can yield considerable information on the molecular level system that can lead to variety of nonlinear optical processes like limiting,switching and bistability.Metallo-porphyrins and metallophthalocyanines form an important class of electronic materials because of the large p-electron conjugation over two-dimen-sional molecular structure[4,5].Interest in ad-vanced electronic and photonic materials recently has led to the exploration of conjugated polymers of more complex units,such as porphyrins[6].The high polarizability and optical oscillator strength of the porphyrin macrocycles gives these materials remarkable nonlinear optical(NLO)behaviour, making them potentially useful for ultrafast switching technologies.High values of the nonlin-ear refractive index n2(which is proportional to the real part of the third order susceptibility v(3)) are essential for electro-optical and all-optical switching[6],whereas high nonlinear absorption coe?cients,b(proportional to the imaginary part of v(3))are important for optical limiting[7].The architecture of the porphyrin macrocycles is important for developing materials with optimum nonlinearity and response times[8].Structural modi?cations to the porphyrin ring can be ex-pected to yield molecules with diverse photophys-ical and photochemical properties that will in turn a?ect their optical nonlinearity.This would lead to an increase in a variety of excited state pro-cesses including enhanced internal conversion and intersystem crossing(ISC),ion-association,excita-tion energy transfer,photoinduced electron trans-fer,etc.[9].Such e?ects can be conveniently harnessed to enhance the third order nonlinearity and nonlinear absorption properties,hence to de-velop promising materials for various applications. Excited state absorption(ESA)is the most impor-tant mechanism leading to optical limiting in por-phyrins[10–12].Our group has been involved in studies on a class of porphyrins,known as tetratol-ylporphyrins,for achieving higher optical limiting performance and nonlinear absorption.The tetra-tolylporphyrins synthesized have higher third or-der nonlinearities[10,11,13]and e?orts are being made to attain large excited state absorption cross-sections through structural modi?cations. In this paper,we discuss the nonlinear absorption properties of oligomers based on Sn(IV)TTP scaf-fold that lead to an interesting nonlinear switching behaviour.
2.Molecular structure and linear optical properties
The nomenclature of monomer and dimer molecule is meso-5,10,15,20-(tetratolyl)porphy-rinato tin(IV)dihydroxide;[(TTP)Sn IV(OH)2] and[l-[5,10,15-tri(p-tolyl)-20-[4-[2-[4-[10,15,20-tri(p-tolyl)-5-porphyrinyl]phenoxy]ethoxy]phenyl] porphyrinato]]di(tin)(IV)tetrahydroxide;[(TriTP)–Sn IV(OH)2]–O(CH2)2O–[(TriTP)Sn IV(OH)2],res-pectively.Dimer molecule has two monomers linked at meso position with ethoxy spacer.Mono-mer and dimer are synthesized following the procedure reported in the literature[14,15].For simplicity we mention them as SnTTP and Sn–Sn(TTP)2in this paper.Sn IV porphyrin based,?axial-bonding?type hybrid trimers and hexamers are constructed by employing?building-block?ap-proach.The approach involves simple inorganic reactions such as axial bond formation of main group element containing porphyrins and inser-tion of metal/metalloid ions into the porphyrin cavity.The architecture of the trimer arrays[16] is such that Sn IV complex of meso-5,10,15,20-(tet-ratolyl)porphyrin forms the basal sca?olding unit, the free-base,Ni II porphyrins occupy the two axial sites via an aryloxy bridge.The nomenclature of the porphyrin trimer arrays discussed here is as follows:(free-base porphyrin)2(tin(IV)porphy-rin)”[(TTP)–Sn IV(H2TriTP(O))2]and(nickel(II) porphyrin)2(tin(IV)porphyrin)”[(TTP)–Sn IV(Ni-TriTP(O))2].For simplicity these trimers are re-ferred as Sn–(H2)2(TTP)3and Sn–Ni2(TTP)3, respectively.The scheme of construction of
P.P.Kiran et al./Optics Communications252(2005)150–161151
hexamer arrays employs a synthetic protocol involv-ing sequential?organic?and?inorganic?reactions con-ducted,respectively,at the peripheral meso-phenyl ring and the central Sn IV ion of the porphyrin scaf-fold.The architecture of hexamers[15]are based on a covalently linked Sn IV porphyrin dimer,with each of the two Sn IV porphyrins centers trans-axi-ally ligated to two free-base,zinc(II)porphyrins. The nomenclature of the hexamers is given as follows:[(TTP)–Sn IV(H2TriTP(O))2]–O(CH2)2O–[(TTP)–Sn IV(H2TriTP(O))2]and[(TTP)–Sn IV (ZnTriTP(O))2]–O(CH2)2O–[(TTP)–Sn IV(ZnTriT-P(O))2].These arrays are referred as Sn2–(H2)4(TTP)6and Sn2–Zn4(TTP)6arrays.The molecular structure and UV–VIS absorption prop-erties of the trimers and hexamers are reported elsewhere[15,16].
A comparison of the UV–VIS spectrum of a gi-ven trimer and hexamer with the spectra of the cor-responding monomeric porphyrin suggested that the absorption peaks of these array are in the same range as those of the reference compounds.In addi-tion,the molar absorptivities at the peak maxima (e)values of the bands due to trimers and hexamers are nearly equal to the sum of those due to their constituent monomers.Minor variations in the spectral features of the trimers with respect to the corresponding monomers are ascribed to the?sub-stituent e?ects?,i.e.,di?erences in the axial ligands of Sn IV porphyrins and the meso substituents of the free-base porphyrins/metalloporphyrins.These indicate that there is minimal perturbation of the electronic structures of the individual macrocyclic p-systems in these arrays.Speci?cally there exists no indication of the presence of exciton coupling between the porphyrin rings,i.e.,basal–basal,ba-sal–axial,or axial–axial interaction in these arrays. On the other hand,the singlet state activities of these oligomers are quite di?erent from those of the precursor reference compounds as probed by steady-state?uorescence.
In the case of trimers,?uorescence due to both the basal and axial porphyrins is considerably quenched in comparison with that due to the monomeric chromophores.Whereas,the spectral shapes and the wavelengths of maximum emission for the individual chromophores of these arrays re-mains close to those due to the corresponding monomeric entities.Thus,the singlet state energy values(E0–0values of H2,Zn II and Sn IV porphy-rins are1.94,2.07,and2.04eV,respectively)of the individual components of these arrays are as-sumed to be essentially similar to those of their constituent monomers.In the case of hexamers, strong quenching of?uorescence is observed.The percent quenching is close to100,with the band that is characteristic of Sn IV porphyrin emission being totally absent in the spectra.This is in con-trast with the partial quenching observed in case of trimers.In trimer molecules,photoinduced elec-tron transfer(PET)occurs from the axial porphy-rin to the basal Sn IV porphyrin and excitation energy transfer(EET)occurs from basal Sn IV por-phyrin to axial acceptors.In the case of hexamers, in addition to the EET from the basal Sn IV por-phyrin to its own two axial free-base acceptors, additional energy transfer from a given Sn IV por-phyrin to the free bases ligated at the neighbouring Sn IV centers,i.e.,?trans-axial?energy transfer is likely to occur leading to more e?cient quenching.
A very high e?ciency of energy transfer from the basal Sn IV porphyrin to the axial acceptors is ob-served in these axial-bonding type donor–acceptor hexamers[15]and less prominent PET reaction from axial acceptor to basal Sn IV porphyrin can rationalize the100%quenching observed for the ?uorescence due to tin(IV)porphyrins of these hexameric assemblies.A generalized energy level diagram illustrating the singlet state dynamics and charge transfer(CT)states pertaining to the photoactive arrays of trimer and hexamer are re-ported earlier[15].The e?ect of PET,EET and the CT states formed in these oligomers are found to vary the singlet state properties and these e?ects were considered while estimating the?gures of merit for nonlinear absorption.
Fluorescence lifetimes and the respective?uo-rescence yields of these porphyrin molecules stud-ied in dichloromethane as solvent are given in Table1.Fluorescence lifetimes are measured using time correlated single photon counting(TCSPC) technique explained in the next section.All these molecules have bi-exponential decays for s S
1
repre-senting fast and slow decay.For SnTTP the life-time is0.562;1ns.In the case of trimers,s S
1
has increased to0.74and5.93ns in Sn–(H2)2(TTP)3
152P.P.Kiran et al./Optics Communications252(2005)150–161
trimer and with metal substitution in case of Sn–
Ni2(TTP)3s S
1is$0.62and2.13ns.As the array
is becoming larger,the contribution of slowly decaying(long lived)component has increased. In case of Sn2–(H2)4(TTP)6,S1has a tri-exponen-tial decay with0.454,1.95and7.25ns whereas for Sn2–Zn4(TTP)6it is a bi-exponential decay of 0.667and1.73ns.The lifetimes of the?rst excited singlet state have varied considerably with the me-tal substitution in hexamers.Substitution of Zn as central metal atom in porphyrin ring is reported to vary the singlet state properties and triplet state formation quite signi?cantly[17].As the excitation pulse is6ns,the longer S1lifetime of Sn2–(H2)4(TTP)6will help in enhanced ESA and ISC, which lead to better optical limiting performance. Fluorescence decay curves for tin monomer,tri-mer,hexamer having Sn and H2as two centers are shown in Fig.1(a).Fig1(b)shows the varia-tion in the?uorescence lifetimes with the substitu-tion of Zn in the hexamer array.PET and EET are found to be responsible for the observed variation in the singlet state properties.PET from ground-state free-base porphyrin to the singlet-state Sn IV porphyrin leads to a charge transfer state of Sn IV Pà–H2P+and involves free-energy changes leading to formation of charge transfer states. These charge transfer states lead to delocalization of singlet states and the?uorescence emission wavelength is red shifted quite considerably.
3.Experimental details
Fluorescence lifetime of the?uorphores is mea-sured using various methods.Among all,time cor-related single photon counting(TCSPC)is rated as the best method.TCSPC is a digital technique, which counts the photons that are time correlated with the excitation pulse.The heart of the method is a time-to-amplitude converter.A mode locked Tsunami picosecond laser second harmonic (405nm,FWHM$1.2ps)operated at4MHz is used as the excitation source.The decay measure-ments are done using a?uorescence lifetime spec-trometer(Model5000U,IBH,UK).The excitation beam is focused onto the sample and ?uorescence is collected at right angles to the exci-tation beam and is detected by a MCP-PMT (Hamamatsu R3809U)after passing through a monochromator.Signal from the PMT is fed to the discriminator and the output of the discrimina-tor is used as a stop signal for TAC(time to ampli-tude converter).The start signal is derived from the high-speed silicon detector(Thor Labs Inc., DET210).The photodiode signal is converted to TTL by pulse converter(IBH,Model TB-01)and the output is used as a start pulse for TAC.The TAC output is fed to the MCA card(Oxford Corp.,UK).Repetitive laser pulsing and emitted
Table1
Fluorescence lifetimes and%yields of Sn(IV)TTP oligomers
Porphyrin s S
1
[ns],(%?uorescence yield)
SnTTP0.562(71),1(28)
Sn–Sn(TTP)20.57(95),4.94(5)
Sn–(H2)2(TTP)30.744(71),5.93(28)
Sn–Ni2(TTP)30.62(70),2.13(29)
Sn2–(H2)4(TTP)60.454(28),1.95(23),7.25(47)
Sn2–Zn4(TTP)60.667(30),1.73(69)
P.P.Kiran et al./Optics Communications252(2005)150–161153
photon collection produced a histogram of time versus counts,representing the?uorescence decay. The data analysis is carried out using the software provided by IBH(DAS-6)that is based on recon-volution technique incorporating iterative nonlin-ear least square methods.
Frequency doubled Nd:YAG lasers with25ps and6ns pulse widths,10Hz repetition rate are used for the nonlinear absorption experiments. The porphyrin solutions in chloroform are used for the experimental studies.Open aperture Z-scan [18]studies are carried out by focusing the input beam on to the sample with linear transmission of approximately75%at532nm using lenses of 500mm and of125mm focal length to60and 30l m spot size at focus in case of25ps and6ns pulses,respectively,and the transmitted light is col-lected with a fast photodiode.The peak?uences used in the Z-scan experiments with25ps pulses are approximately in the range of5–52GW cmà2. The standard f/5geometry is used for the optical limiting studies[19].The linear transmission of the porphyrin solutions is approximately70–75% for1-mm path length of the sample at the excita-tion wavelength.The input?uence is varied in the range of30l J cmà2to70J cmà2in the nanosec-ond regime.The optical limiting and Z-scan studies are performed at the concentration of$10à4M ensuring identical concentration conditions for both picosecond and nanosecond regimes.
4.Nonlinear absorption properties
The nonlinear absorption behaviour observed in these hybrid arrays is totally di?erent at nano-second and picosecond timescales.In the picosec-ond regime the behaviour switches from RSA to SA and then again to RSA as the intensity in-creases.However,in the nanosecond regime all these molecules show good RSA in the intensity range studied.No switching from RSA to SA is observed with the nanosecond excitation.
4.1.Excitation by25ps pulses
At lower intensities for picosecond pulses these materials show only RSA.With increasing inten-sity an interesting changeover from RSA to SA and then back to RSA is observed.SnTTP mono-mer shows a regular RSA behaviour at lower con-centrations(corresponding to75–80%linear transmission at532nm)and at lower intensities. At higher intensities the ESA saturates and SA fol-lowed by RSA is observed as shown in Fig.2(a). As the intensity is further increased to $38GW cmà2,the nonlinear absorption shows a sudden transition to RSA at higher intensities within SA behaviour(Fig.2(b)).In the case of di-mer,at lower intensities only RSA is observed (Fig.3(a)),and as the intensity increases,the switching of the nonlinear absorption from RSA to SA and then back to RSA is observed(Fig. 3(b)).As the intensity increases the SA behaviour after RSA goes down and the RSA behaviour be-comes more dominant.
154P.P.Kiran et al./Optics Communications252(2005)150–161
In the case of oligomers with Sn(IV)TTP sur-rounded by free-base porphyrin(H2TTP),at lower concentrations and at lower intensities RSA is ob-served and with increasing intensity saturation of the ESA is observed.The saturation has increased with increasing input intensity.The open aperture Z-scan curves for Sn–(H2)2(TTP)3are shown in Fig.4.Sn2–(H2)4(TTP)6also shows similar behav-iour and at higher intensities the saturation has in-creased quite considerably.While replacing H2TTP in axial position with NiTTP lead to a to-tal reversal in the nonlinear absorption behaviour. For Sn–Ni2(TTP)3,at lower concentrations,at lower input intensities saturation of absorption alone is observed.With gradual increase in the in-put intensity RSA followed by initial SA is ob-served(Fig.5(a))and at higher intensities pure RSA was observed(Fig.5(b)).As the intensity is increased the RSA started to take over and at higher intensities RSA completely dominates due to TPA assisted ESA.At higher concentrations (60%linear transmission at532nm)the behaviour remained pure RSA as shown in Fig.5(b).For Sn–Ni2(TTP)3with532nm excitation falling in the edge of the absorption band,the lowest of the S1 energy levels get excited and therefore one expects more localization of the energy leading to SA at lower intensities,whereas,at higher intensities TPA dominates and assisted by ESA shows pure RSA.However,for Sn2–Zn4(TTP)6at lower con-centrations,a transition from SA to RSA due to two-photon/multi-photon absorption is observed. The open aperture Z-scan curve looks similar to that shown in Fig.5(a)and with increasing inten-sity we observe more contribution from RSA. At higher concentrations and the intensity of
P.P.Kiran et al./Optics Communications252(2005)150–161155
28.5GW cmà2,saturation of absorption due to ex-cited states is observed(similar to Fig.4(a))with transmittance at focus going up to0.84and the curves appear slightly broader indicating the con-tribution of ESA.As the intensity has increased to$52GW cmà2,RSA is observed after satura-tion of absorption due to TPA(similar to that shown in Fig.2(b)).From the open aperture Z-scan curves given in Fig.2–5,it is very clear that under the similar experimental conditions,the nonlinear absorption response of these molecules is very di?erent from that of each other,clearly indicating the e?ect of the presence of di?erent central metal atoms in the porphyrin oligomer structures.Further if the nonlinear absorption is due to the solvent at higher intensity due to?fth order or higher order processes,we will not ob-serve the saturation behaviour in the curves at the focal point(Fig.4).This is an indirect con?r-mation that the observed behaviour is due to the saturation of the higher excited states of the por-phyrins molecule.In order to con?rm that the nonlinear absorption at higher intensities are due to the porphyrins and not due to the solvent,we carried out the Z-scan studies in pure solvent at intensity ranges of10–52GW cmà2.The observed RSA behaviour at the focal point is negligible compared to the signals seen with the porphyrins solution(2%variation compared to50%variation in porphyrins)and the e?ect of the solvent has been accounted for in all calculations.Though the ESA,TPA and the lifetimes of the higher ex-cited states appears to play an important role in the nonlinear absorption of all these oligomers, TPA is more dominant in oligomers having me-tal–metal porphyrin macrocycles(Sn–Ni,Sn–Sn, Sn–Zn)and is absent in molecules having metal–free-base porphyrin interaction.
Observations of RSA at lower intensities and then SA due to saturation of ESA with picosecond pulse excitation has been reported earlier in cad-mium texaphyrin[20]and in HITCI[21,22]. Depending on the input pulse duration,nonlinear absorption in these materials normally occurs through transitions from S0!S n states by instan-taneous TPA or from S0!S1!S n states by a two-step resonant ESA(if S1!S n occurs after vibrational transitions or di?usion within the sin-glet states)or T1!T n states by means of ESA. From the equilibrium level S1the molecules may relax radiatively or nonradiatively to the ground state or transfer to the lower level of triplet mani-fold,T1.E?cient RSA for picosecond pulses re-quires that the recovery rate from the S1state be slow compared to the optical pumping rate.In-tra-band vibrational relaxation times also play an important role for RSA.The higher excited states of the singlet manifold relax to the lower vibra-tional states,leading to absorption of the pump from the lower singlet sublevels to the higher ex-cited states through ESA.In metalloporphyrins, N and L bands exist at higher energies(317nm) in addition to the low energy B and Q bands. The N and L bands are more prominent in SnTTP compared to NiTTP and ZnTTP,whereas in
156P.P.Kiran et al./Optics Communications252(2005)150–161
H2TTP,N and L bands are not prominent.At higher excitation intensities,the possibility of reso-nant two-photon transition to the N,L bands from the lower singlet states increases.At the intensities and the pulse width used one need to consider the e?ect of multi-photon absorption (MPA)also.Although MPA in some of the aro-matic hydrocarbons like benzene and toluene is predicted and later observed experimentally lead-ing to nonlinear absorption,we have not observed any signi?cant nonlinear absorption in the chloro-form solvent used.Two-photon and three-photon processes leading to optical limiting are well re-ported in various organic compounds[23].For porphyrins the intersystem crossing time(s ISC), which is of the order of few nanoseconds in general and few hundreds of picoseconds in some speci?c cases,is of minor consequence because of the 25ps pulse width of the laser.For the picosecond excitation we therefore can neglect intersystem crossing and hence the contribution of the T1state, which makes the singlet states responsible for the observed behaviour at these time scales.
The values of excited state parameters r ex/r0, TPA coe?cient(b in cm GWà1),TPA cross-sec-tion(r TPA)and s sn are estimated using a general-ized?ve-level model and from the rate equations. The generalized?ve-level model e?ectively be-comes a three-level model for picosecond pulse excitation as the contribution from the triplets can be neglected,since the intersystem crossing from singlet to triplet state is very less.The di?er-ential equations are?rst de-coupled and then inte-grated over time,length,and along the radial direction,and then are solved numerically using Runge–Kutta fourth order method.Assuming the input beam to be a Gaussian,the limits of inte-gration for r,t,and z are varied from0to1,à1 to1,and0to L(length of the sample),respec-tively.Typical number of slices used for r,t,and z are60,30,and5,respectively.r1,r ex,b and s ISC are then estimated through least square?t of the experimental data[24].The lifetime of the higher excited singlet state S n(s Sn)has been evaluated and the lifetimes of the?rst excited singlet state is taken as given in Table1.Table2gives the absorption cross-section and lifetime of the excited states and the TPA coe?cient(b)and cross-section (r TPA).The TPA cross-section is calculated using the relation[25]b?N0r TPA;where h is the Planck?s constant,m is the frequency of light,and N0is the number molecules per unit volume.From the Table2it is clear that the TPA cross-section is large and comparable with the values of 11,000GM(1GM=10à50cm4s photonà1mole-culeà1)reported with dendrimer molecules com-prising29repeat units[26].The most plausible explanation for such a large TPA cross-section in our case is due to the fact that PET,EET and ?trans-axial?energy transfer processes occurring simultaneously in the same porphyrin oligomeric structure leading to more delocalization of the sin-glet states thereby causing considerable changes in the absorption from the S1to the S n states,which follows the square law for intensity dependence, leading to enhanced TPA.Such a delocalization can further enhance TPA assisted by ESA from the singlet states.Such drastic enhancement of TPA in porphyrins has been reported due to the resonant absorption and with the substitution of electron accepting groups[27,28].Out of the di?er-ent oligomers studied,the trimer having Sn,Ni porphyrins linked axially has very high r TPA.This could be due to the fact that the excitation wave-length is in resonance with the S0–S1transition thus increasing the possibility of ESA assisting TPA.
The lifetimes of the excited singlet states(s Sn) are evaluated using theoretical?ts(Table2).All these oligomers are found to have the excited states relaxing in few picoseconds to few hundreds of picosecond and compare well with the reports in the literature.Sn–H arrays show longer Table2
Excited state parameters r1/r0,s sn and TPA coe?cient b with 25ps pulse excitation
Porphyrin(r1/r0)s Sn
(ps)
b
(cm GWà1)
r TPA a
(10à46cm4s) SnTTP18.32600.45 2.7
Sn–Sn(TTP)2 3.007.5 1.5013.6
Sn–(H2)2(TTP)3 3.13500––
Sn–Ni2(TTP)335.7050 1.45396.0
Sn2–(H2)4(TTP)6 1.93500––
Sn2–Zn4(TTP)6 2.39150.9015.7
a The error in the r
TPA
is10%.
P.P.Kiran et al./Optics Communications252(2005)150–161157
s Sn$500ps whereas rest of the molecules shows faster s Sn.Ultrafast relaxations of the order of few hundred femtoseconds are well known in por-phyrin-acceptor systems due to electron transfer [29].Photoinduced charge separation,thermal charge recombination electron transfer due to por-phyrin localized charge transfer character in a di-rectly linked pyromellitimide-(porphyrinato) Zn(II)complex and similar donor–acceptor sys-tems are reported to be in the timescales of770 and5200fs[30].Competition between internal conversion and energy transfer in the upper ex-cited singlet state of the porphyrin-ruthenium complexes are also reported[31].Lammi et al.
[32]reported energy and charge transfer between the adjacent states leading to excited state quench-ing at timescales611ps and between di?erent sites by super exchange assisted energy transfer at time-scales of655ps in diphenyl ethyne linked porphy-rin dyads and triads and the relaxation rates can be tuned using the porphyrin-linker connection motif.Ultrafast excitation energy transfer pro-cesses are observed to be in the order of 12±3ps in Zn(II)porphyrin box[33].Increasing number of porphyrin units has also reported to accelerate the relaxation dynamics of the lowest excited states from4.5ps for dimer to0.3ps for hexamer[34].O?Keefe et al.[35]reported a two-component decay,of approximately700fs and 170±50ps due to exciton–exciton annihilation and exciton di?usion to recombination centers on the polymer chain from femtosecond transient photoinduced transmission measurements on Zinc conjugated porphyrin polymer.Similar faster de-cay of13±5ps is also reported for dimer[35] due to the rotational di?usion of the excited mole-cule in solution.Relaxations of$6ps are also re-ported in ethylene bridged side-to-side OEP porphyrin dimer[36].Excited-state energy transfer is reported to be operative at timescales of3.5and 10ps in p-phenylene linked porphyrin dimers[37], which varies with the bridge linker.Ultrafast kinetics of a hexameric benzo-porphyrin com-pound investigated by femtosecond transient absorption spectroscopy,shows that in the hexa-mer a20ps decay component is present which is attributed to an intramolecular interchromophoric excited-state process[38].In cofacial lanthanide porphyrin macrocycles two relaxation processes with time constants of$1.5and10ps are reported [39].Energy transfer to the nearest porphyrin in chelate assembly separated by approximately15–18.5A?is reported to occur in$10ps,which varies with the separation[40].
4.2.Excitation by6ns pulses
With6ns pulse excitation the nonlinear absorp-tion behaviour is completely di?erent compared to that observed with25ps pulses.OL curves for monomer SnTTP,trimer Sn2–(H2)2(TTP)3and hexamer Sn2–(H2)4(TTP)6at$75%linear trans-mission at532nm shown in Fig.6clearly indicates the enhanced limiting behaviour as one moves to higher homologues.Fig.7(a)and(b)shows the variation in the limiting curves for SnTTP and Sn–Sn(TTP)2at di?erent linear transmissions of 85%and70%.With the introduction of heavier metalloporphyrin in the axial position in place of free-base porphyrin,in trimer and hexamer do-nor–acceptor homologues,lead to slightly reduced limiting response.OL curves for hexamers with free-base and Zn porphyrins in axial position are shown in Fig.8.Though the limiting threshold has not varied greatly,the onset of limiting varies certainly,with lower values for the oligomers. Throughput?uences from these hybrids are as
158P.P.Kiran et al./Optics Communications252(2005)150–161
low as35–52mJ cmà2with input?uences in the range of$26–74J cmà2making these arrays very good optical limiters at higher intensities.Decreas-ing linear transmission to$60%,we are able to achieve much better limiting performance in all these molecules.With increase in the concentra-tion the ESA increases,thereby leading to im-proved nonlinear absorption behaviour.No aggregation is observed in the porphyrin solutions even at higher concentrations and we have not ob-served any scattering due to thermal blooming of the solution.
Limiting threshold values for the oligomers with6ns pulses are shown in Table3.Figure of merit(r ex/r0),which describes the capability of a material for optical limiting,and s ISC estimated from the theoretical?ts is also given in Table3. The contribution from all the processes like PET and EET and both the radiative and nonradiative processes towards the lifetimes are taken as the e?ective singlet lifetime used in the rate equations. Singlet state lifetime and the ESA from S1!S n in addition to T1!T n are found to be responsible for the enhanced limiting performance of higher homologues.Simultaneous occurrence of strong EET and less prominent PET lead to a drastic change and stabilization of S1states in these mol-ecules,making the S1state metastable in compar-ison with the excitation laser pulse width.The
Table3
Limiting threshold and excited state parameters of the SnTTP
arrays having75%linear transmission,with6ns pulse excita-
tion at532nm
Porphyrin I1/2(J cmà2)r ex/r0s ISC(ps)
SnTTP12.30 3.241000
Sn–Sn(TTP)20.1621.53180
Sn–(H2)2(TTP)3 2.917.26380
Sn–Ni2(TTP)3 3.46 6.21550
Sn2–(H2)4(TTP)60.4619.45220
Sn2–Zn4(TTP)6 1.16 6.73600 P.P.Kiran et al./Optics Communications252(2005)150–161159
e?ective ESA cross-sections from both singlets and triplet states is taken as r ex.Even though the con-tribution due to ESA from S1to S n is present in these molecules as the lifetime of S1is longer and comparable to laser pulse width,due to the low ?uorescence yields most of these molecules seem to transfer to T1with a time given by the longer decay.However high triplet yields in these mole-cules indicate that intersystem crossing plays an important role in these systems at the nanosecond timescales.Such a large intersystem crossing rate has been reported in the unaggregated solutions of edge linked zinc porphyrin oligomers[41]and in monomer,dimer and polymer?lms[42].The intersystem crossing time obtained from the theo-retical?ts is around180–600ps for these oligo-mers.Similar decay times are reported in zinc porphyrin oligomers[43]obtained from pump-probe measurements using a0.8ps pulse.Highly e?cient triplet–triplet energy transfer and en-hanced intersystem crossing is reported in rigidly linked metal and free-base porphyrin hybrids[43] and also in porphyrins linked via Ruthenium com-plex[44].As the excitation pulse is of6ns dura-tion,the longer lifetimes of S1in these arrays will help in enhanced ESA from the S1states,in addi-tion to the ESA from the triplet states,which lead to better optical limiting performance.With the introduction of ZnTTP in hexamer and NiTTP in trimer in the place of the free-base TTP,we have observed reduced limiting performance of the mol-ecule,due to the variation in the singlet state prop-erties.When compared with the H2TTP,NiTTP and ZnTTP monomers these oligomers show a better limiting performance under the similar experimental conditions.
5.Conclusions
The nonlinear absorption processes of porphy-rin arrays based on Sn(IV)sca?old are studied in the picosecond and nanosecond timescales.In the picosecond regime,these molecules show SA at higher intensities after the initial RSA at lower intensities.At very high intensities RSA again dominates due to TPA.The lifetimes of the excited singlet states and the presence of TPA are found to be leading to the observed behaviour.Though the cross over from RSA to SA and back to RSA is observed in these hybrid arrays,the Sn–Ni2(TTP)3 has shown predominantly RSA which makes it a useful material for picosecond optical limiting.In the nanosecond regime,the optical limiting perfor-mance has increased as one move to higher homo-logues.Within trimer and hexamers,substitution of heavier metalloporphyrin in the axial positions has reduced the limiting performance slightly. Whereas,linearly linked Sn–Sn dimer showed a better limiting performance than the axial-bonding type trimers and hexamers.Such a crossover from RSA to SA and then back to RSA with25ps pulses and large TPA cross-section makes these materials potential candidates for various intensity dependent ultrafast nonlinear optical switching purposes.
Acknowledgements
Financial support from the Department of Atomic Energy–Board of Research in Nuclear Sciences,and the Defence Research Development Organization,India,is acknowledged.P.P.Kiran thanks the Council for Scienti?c and Industrial Research,India,for the Senior Research Fellow-ship.We thank National Center for Ultrafast Pro-cesses(Chennai,India)for extending us picosecond?uorescence lifetime measurement facility.
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第一篇、教你学会看电路图轻松修手机 一、一套完整的主板电路图，是由主板原理图和主板元件位置图组成的。 1.主板原理图，如图： 2.主板元件位置图，如图：
主板元件位置图的作用：是方便用户找到相应元件所在主板的正确位置。而主板原理图是让用户对主板的电路原理有所了解，知道各个芯片的功能，及其线路的连接。 二、相关名词解释 电路图中会涉及到许多英文标识，这些标识主要起到了辅助解图的作用，如果不了解它们，根本不知道他们的作用，也就根本不可能看得懂原理图。所以在这里我们会将主要的英文标识进行解释。希望大家能够背熟记熟，同时希望大家多看电路图，对不懂的英文及时查找记熟。 如图：
以上英文标识在电路图上会灵活出现，比如“扬声器”是“SPEAKER” ，它的缩写就是“SPK”，“正极”是“positive” ，缩写是“P” ，那么如果在图中标记SPKP，那么就证明它是扬声器正极。所以当有英文不明白的时候，可以将它们拆开后再进行理解，请大家灵活运用。
第二节主板元件位置图 一、元件编号 每一个元件在主板元件位置图中，都有一个唯一的编号。这个编号由英文字母和数字共同组成。编号规则可以分成以下几类： 芯片类：以U 为开头，如CPU U101 接口类：以J 为开头，如键盘接口J1202 三极管类：以Q 为开头，如三极管Q1206 二级管类：以D 为开头，如二极管D1102 晶振类：以X 为开头，如26M 晶体X901 电阻类：以R 或VR（压敏电阻）为开头，如电阻R32 VR211 电容类：以C 为开头，如电容C101 电感类：以L 为开头，如电感L1104 侧键类：以S 为开头，如侧键S1201 电池类：以 B 为开头，如备用电池B201 屏蔽罩：以SH 为开头，如屏蔽罩SH1 振动器：以M 为开头，如振子M201 还有一部分标号是主板上的测试点，以TP 为开头。 二、查找元件功能 用户可以根据相应的元件编号去查找主板原理图，从而了解此元件的作用。随便拿块主板作为示例。 如果想了解某一个元件的主要功能（图中红圈内元件） 如图：
第二部分原理篇 第一章手机的功能电路 ETACS、GSM蜂窝手机是一个工作在双工状态下的收发信机。一部移动电话包括无线接收机(Receiver)、发射机(Transmitter)、控制模块(Controller)及人机界面部分(Interface)和电源(Power Supply)。 数字手机从电路可分为，射频与逻辑音频电路两大部分。其中射频电路包含从天线到接收机的解调输出，与发射的I/Q调制到功率放大器输出的电路；逻辑音频包含从接收解调到，接收音频输出、发射话音拾取(送话器电路)到发射I/Q调制器及逻辑电路部分的中央处理单元、数字语音处理及各种存储器电路等。见图1-1所示 从印刷电路板的结构一般分为：逻辑系统、射频系统、电源系统，3个部分。在手机中，这3个部分相互配合，在逻辑控制系统统一指挥下，完成手机的各项功能。 图1-1手机的结构框图 注：双频手机的电路通常是增加一些DCS1800的电路,但其中相当一部分电路是DCS 与GSM通道公用的。 第二章射频系统 射频系统由射频接收和射频发射两部分组成。射频接收电路完成接收信号的滤波、信号放大、解调等功能；射频发射电路主要完成语音基带信号的调制、变频、功率放大等功能。手机要得到GSM系统的服务,首先必须有信号强度指示,能够进入GSM网络。手机电路中不管是射频接收系统还是射频发射系统出现故障,都能导致手机不能进入GSM网络。 对于目前市场上爱立信、三星系列的手机,当射频接收系统没有故障但射频发射系统有故障时,手机有信号强度值指示但不能入网；对于摩托罗拉、诺基亚等其他系列的手机,不管哪一部分有故障均不能入网,也没有信号强度值指示。当用手动搜索网络的方式搜索网络时,如能搜索到网络,说明射频接收部分是正常的；如果不能搜索到网络,首先可以确定射频接收部分有故障。 而射频电路则包含接收机射频处理、发射机射频处理和频率合成单元。 第一节接收机的电路结构 移动通信设备常采用超外差变频接收机，这是因为天线感应接收到的信号十分微弱,而鉴频器要求的输人信号电平较高,且需稳定。放大器的总增益一般需在120dB以上,这么大的放大量,要用多级调谐放大器且要稳定,实际上是很难办得到的，另外高频选频放大器的通带宽度太宽,当频率改变时,多级放大器的所有调谐回路必须跟着改变，而且要做到统一调谐,
一，手机原理图的种类： 手机电路图共分四类：1，方框图；2，整机电原理图；3，元件排列图；4，彩图。 1，方框图： 利用方块形式粗略概述手机的结构与工作原理，方便初学者掌握手机的结构与工作原理，为初学者读懂电原理图打下基础。 2，整机电原理图： 利用电子原件符号清楚表示手机中各元器件的连接和工作原理，方便维修时分析电路原理及故障分析。 3，元件排列图： 利用元件编号在板位图上标明元件所在位置，方便维修时寻找元件在板上的位置。 4，彩图： 即手机照片，方便维修时对照板元件缺损，错位，元件方向。 二，手机电路图的读解原则： 1，读图前要打好电子基础，熟悉各种电子元器件符号，特性和用途；电子元器件在电路中的接法；电路中的电流，电压，电阳之间的关系（欧姆定律）。 2，先读懂方框图，大根了解本机的结构（如那种电源结构，那种时钟结构）；然后按所学的原理去分析原理图。 3，读图时先弄懂直流供电电路，后弄懂交流信号通路。 4，手机电路图是有规律的，一般电源居左下；控制居右下。左射频右逻辑；上收下发中本振。三，手机电路图的读解方法： 1，电源电路读图要点： 1），先了解本机属那种电源结构（分三种）以电源集成为核心。 2），从尾插或电池脚开始，找出电池电压（VBATT，B+）输入线；电池电压一般直接供到电源集成块，充电集成块，功放，背光灯，振铃，振动等电路；也可从上述电路回找。 3），在电源集成块，键盘，内联座处找到开机触发线（ON/OFF或标有开关符号）。 4），在电源集成块上找出各路电压输出线（包括电压走向，电压值多少，是恒定的还是跳变的，在那个单元上可以测到该电压）。 1）VDD--逻辑电压给CPU，字库，暂存等电路（1。8V/2。8V） 2）SYN-VCC（XVCC）时钟电压，使13M电路工作（2。8V） 3）AVCC--音频电压（2。8V） 4）VREF--中频电压（2。8V跳变） 5）3VTX--发射电压（3V跳变） 6）SYN-VCC---频合电压（2。8V） 7)VRTC--实时时钟电压（3V） 8）SIM-VCC--SIM卡电路电压（3V/5V跳变） 9）RST（PURX）--复位信号（0-2。8V） 4），在CPU与电源集成块间找到开机维持线（WD-CP，WATCCH DOG）。 5），从键盘，电源集成块旁边的开关符号到CPU找到关机检测线。 2），充电电路读图要点： 1），以电源集成块或充电集成为核心，找到充电电路。 2），从充电接口（尾插）到电源集成块或充电集成块找出外电输入线
手机供电电路结构和工作原理 一、电池脚的结构和功能。 目前手机电池脚有四脚和三脚两种：（如下图） 正温类负正温负 极度型极极度极 脚脚脚 （图一）（图二） 1、电池正极（VBATT）负责供电。 2、TEMP：电池温度检测该脚检测电池温度；有些机还参与开机，当用电池能开机，夹正负极不能开机时，应把该脚与负极相接。 3、电池类型检测脚（BSI）该脚检测电池是氢电或锂电，有些手机只 认一种电池就是因为该电路，但目前手机电池多为锂电，因此，该脚省去便为三脚。 4、电池负极（GND）即手机公共地。 二、开关机键: 开机触发电压约为2.8-3V(如下图)。 内圆接电池正极外圆接地;电压为0V。 电压为2.8-3V。 触发方式 ①高电平触发：开机键一端接VBAT，另一端接电源触发 脚。 （常用于：展讯、英飞凌、科胜讯芯片平台） ①低电平触发：开机键一端接地，另一端接电源触发脚。 （除以上三种芯片平台以外，基本上都采用低电平触发。如：MTK、AD、TI、飞利浦、杰尔等。） 三星、诺基亚、moto、索爱等都采用低电平触发。
三、手机由电池直接供电的电路。 电池电压一般直接供到电源集成块、充电集成块、功放、背光灯、振铃、振动等电路。在电池线上会并接有滤波电容、电感等元件。该电路常引起发射关机和漏电故障。 四、手机电源供电结构和工作原理。 目前市场上手机电源供电电路结构模式有三种； 1、 使用电源集成块（电源管理器）供电；（目前大部分手机都使用该电路供电） 2、 使用电源集成块（电源管理器）供电电路结构和工作原理：（如下图） 电池电压 逻辑电压(VDD) 复位信号(RST) 射频电压(VREF) VTCXO 26M 13M ON/OFF AFC 开机维持 关机检测 （电源管理器供电开机方框图） 1）该电路特点： 低电平触发电源集成块工作； 把若干个稳压器集为一个整体，使电路更加简单； 把音频集成块和电源集成块为一体。 2）该电路掌握重点: 电 源 管 理 器 CPU 26M 中频 分频 字库 暂存
两小时学会看懂手机电路图 电路图的种类 常见手机维修中的电子电路图有原理图、方框图、元件分布图、装配图和机板图等 (1)原理图 原理图就是用来体现电子电路的工作原理的一种电路图，又被叫做"电原理图"。这种图，由于它直接体现了电子电路的结构和工作原理，所以一般用在设计、分析电路中。分析电路时，通过识别图纸上所画的各种电路元件符号，以及它们之间的连接方式，就可以了解电路的实际工作时情况。原理图又可分为整机原理图，单元部分电路原理图，整机原理图是指手机所有电路集合在一起的分部电路图。 (2)方框图(框图) 方框图是一种用方框和连线来表示电路工作原理和构成概况的电路图。从根本上说，这也是一种原理图，不过在这种图纸中，除了方框和连线，几乎就没有别的符号了。它和上面的原理图主要的区别就在于原理图上详细地绘制了电路的全部的元器件和它们的连接方式，而方框图只是简单地将电路 (3)元件分布图 它是为了进行电路装配而采用的一种图纸，图上的符号往往是电路元件的实物的外形图。我们只要照着图上画的样子，这种电路图一般是供原理和实物对照时使用的。 (4)机板图 机板图的是"印刷电路板图"或"印刷线路板图"，它和元件分布图其实属于同一类的电路图，都是供原理图联系实际电路使用的。 印刷电路板是在一块绝缘板上先覆上一层金属箔，再将电路不需要的金属箔腐蚀掉，剩下的部分金属箔作为电路元器件之间的连接线，然后将电路中的元器件安装在这块绝缘板上，利用板上剩余的金属箔作为元器件之间导电的连线，完成电路的连接。由于铜的导电性能不错，加上相关技术很成熟，所以在制作电路板时，大多用铜。所以，印刷电路板又叫"覆铜板"。但是大家也要注意到：机板图的元件分布往往和原理图中大不一样。这主要是因为，在印刷电路板的设计中，主要考虑所有元件的分布和连接是否合理，要考虑元件体积、散热、抗干扰、抗耦合等等诸多因素，综合这些因素设计出来的印刷电路板，从外观看很难和原理图完全一致；而实际上却能更好地实现电路的功能。 随着科技发展，现在印刷线路板的制作技术已经有了很大的发展；除了单面板、双面板外，还有多面板，
专门找了几个例子，让大家看看。自己也一边学习。 分析一个电源，往往从输入开始着手。220V交流输入，一端经过一个4007半波整流，另一端经过一个10欧的电阻后，由10uF电容滤波。这个10欧的电阻用来做保护的，如果后面出现故障等导致过流，那么这个电阻将被烧断，从而避免引起更大的故障。右边的4007、4700pF电容、82KΩ电阻，构成一个高压吸收电路，当开关管13003关断时，负责吸收线圈上的感应电压，从而防止高压加到开关管13003上而导致击穿。13003为开关管(完整的名应该是MJE13003)，耐压400V，集电极最大电流1.5A，最大集电极功耗为14W，用来控制原边绕组与电源之间的通、断。当原边绕组不停的通断时，就会在开关变压器中形成变化的磁场，从而在次级绕组中产生感应电压。由于图中没有标明绕组的同名端，所以不能看出是正激式还是反激式。 不过，从这个电路的结构来看，可以推测出来，这个电源应该是反激式的。左端的510KΩ为启动电阻，给开关管提供启动用的基极电流。13003下方的10Ω电阻为电流取样电阻，电流经取样后变成电压(其值为10*I)，这电压经二极管4148后，加至三极管C945的基极上。当取样电压大约大于1.4V，即开关管电流大于0.14A时，三极管C945导通，从而将开关管13003的基极电压拉低，从而集电极电流减小，这样就限制了开关的电流，防止电流过大而烧毁(其实这是一个恒流结构，将开关管的最大电流限制在140mA左右)。 变压器左下方的绕组(取样绕组)的感应电压经整流二极管4148整流，22uF电容滤波后形成取样电压。为了分析方便，我们取三极管C945发射极一端为地。那么这取样电压就是负的(-4V左右)，并且输出电压越高时，采样电压越负。取样电压经过6.2V稳压二极管后，加至开关管13003的基极。前面说了，当输出电压越高时，那么取样电压就越负，当负到一定程度后，6.2V稳压二极管被击穿，从而将开关13003的基极电位拉低，这将导致开关管断开或者推迟开关的导通，从而控制了能量输入到变压器中，也就控制了输出电压的升高，
EXPRESS WRITTEN PERMISSION OF QUALCOMM. ITS CONTENTS REVEALED IN ANY MANNER TO OTHERS WITHOUT THE NOT TO BE USED, COPIED, REPRODUCED IN WHOLE OR IN PART, NOR U.S.A. San Diego, CA 92121-17145775 Morehouse Drive QUALCOMM Incorporated Sheet # Content 01A. Table of Content 01B. Revision History 01C. Block Diagram 01D. GPIO Map 02. PM8916 Control and MPP/Clock 03. PM8916 Charging 04. PM8916 GPIO/MPP 05. PM8916 Buck converter 06. PM8916 LDO circuits 07. PM8916 CODEC 08. MSM8916 Control 09. MSM8916: EBI 10. MSM8916: GPIO 11. MSM8916: MIPI and RF Control 12. MSM8916: POWER113. MSM8916: POWER214. MSM8916:GND 15. MEMORY:LPDDR3+EMMC 16. Battery Connector 17. Subboard Connector 18. Mic and Receiver 19. EARPHONE 20. LCD interface and backlight 21. Main/Slave Camera and Flash 22. Sensors 23. SIM/TF card 27. WTR1605L TX 28. WTR1605L RX 29. WTR1605L POWER 30. WTR1605L POWER DISTRIBUTION 31. LTE/W/TD/GSM Antenna Switch 32. TRX_Front-High Band QFE234033. TRX_Front-Low Band QFE232034. RESERVED 35. TRX_UMTS_B1/2/5/836. PRX_B34/39/337. PRX_LTE_HB 38. DRX_Antenna Switch 39. QFE1550 DRX Tunner 40. B7/40/41 DRX Switch 41. B39/B1/B3 DRX Switch 42. WTR2605_SECONDARY PATH 43. WTR2605_POWER DISTRIBUTION 44. Antenna_SECONDARY PATH 45. RESERVED 46. RESERVED 47. CDMA BC0(Voice) TRX 48. ET_APT 50. WIFI FEM Sheet # Content 51. GPS/XO DISTRIBUTOR 52. NFC 49. WCN362024. Keypad/LED/Status indicator 25. Touch Interface 26. Test Point/GND/Shields A B C D D C B A
第一篇、教你学会看电路图轻松修手机My id：42409 My name：Aerlant 既然是教程就不能保证100%是原创,难免会引用老师们的宝贵经验，请您别介意哦！ 只要您认真学习完这些教程，就可以正式步入“专业手机维修”行业成为一名优秀的维修员喽！目的很简单，就是让新会员们、新手们，您加入帅虎论坛是正确的。在这里你可以学习到一些实实在在的维修知识，向更高的一个层次迈进、稳步成长。。。 言归正传！有兴趣的朋友往下看，学习一下： 第一节了解电路图 一、一套完整的主板电路图，是由主板原理图和主板元件位置图组成的。 1.主板原理图，如图：
2.主板元件位置图，如图： 主板元件位置图的作用：是方便用户找到相应元件所在主板的正确位置。而主板原理图是让用户对主板的电路原理有所了解，知道各个芯片的功能，及其线路的连接。
二、相关名词解释 电路图中会涉及到许多英文标识，这些标识主要起到了辅助解图的作用，如果不了解它们，根本不知道他们的作用，也就根本不可能看得懂原理图。所以在这里我们会将主要的英文标识进行解释。希望大家能够背熟记熟，同时希望大家多看电路图，对不懂的英文及时查找记熟。 如图：
以上英文标识在电路图上会灵活出现，比如“扬声器”是“SPEAKER” ，它的缩写就是“SPK”，“正极”是“positive” ，缩写是“P” ，那么如果在图中标记SPKP，那么就证明它是扬声器正极。所
以当有英文不明白的时候，可以将它们拆开后再进行理解，请大家灵活运用。 第二节主板元件位置图 一、元件编号 每一个元件在主板元件位置图中，都有一个唯一的编号。这个编号由英文字母和数字共同组成。编号规则可以分成以下几类： 芯片类：以U 为开头，如CPU U101 接口类：以J 为开头，如键盘接口J1202 三极管类：以Q 为开头，如三极管Q1206 二级管类：以D 为开头，如二极管D1102 晶振类：以X 为开头，如26M 晶体X901 电阻类：以R 或VR（压敏电阻）为开头，如电阻R32 VR211 电容类：以C 为开头，如电容C101 电感类：以L 为开头，如电感L1104 侧键类：以S 为开头，如侧键S1201 电池类：以 B 为开头，如备用电池B201 屏蔽罩：以SH 为开头，如屏蔽罩SH1 振动器：以M 为开头，如振子M201 还有一部分标号是主板上的测试点，以TP 为开头。 二、查找元件功能 用户可以根据相应的元件编号去查找主板原理图，从而了解此元件的作用。随便拿块主板作为示例。
第一篇、教你学会看电路图轻松修手机 既然是教程就不能保证100%是原创,难免会引用老师们的宝贵经验，请您别介意哦！ 只要您认真学习完这些教程，就可以正式步入“专业手机维修”行业成为一名优秀的维修员喽！目的很简单，就是让新会员们、新手们，您加入帅虎论坛是正确的。在这里你可以学习到一些实实在在的维修知识，向更高的一个层次迈进、稳步成长。。。 言归正传！有兴趣的朋友往下看，学习一下： 第一节了解电路图 一、一套完整的主板电路图，是由主板原理图和主板元件位置图组成的。 1.主板原理图，如图：
2.主板元件位置图，如图： 主板元件位置图的作用：是方便用户找到相应元件所在主板的正确位置。而主板原理图是让用户对主板的电路原理有所了解，知道各个芯片的功能，及其线路的连接。 二、相关名词解释 电路图中会涉及到许多英文标识，这些标识主要起到了辅助解图的作用，如果不了解它们，根本不知道他们的作用，也就根本不可能看得懂原理图。所以在这里我们会将主要的英文标识进行解释。希望大家能够背熟记熟，同时希望大家多看电路图，对不懂的英文及时查找记熟。 如图：
以上英文标识在电路图上会灵活出现，比如“扬声器”是“SPEAKER” ，它的缩写就是“SPK”，“正极”是“positive” ，缩写是“P” ，那么如果在图中标记SPKP，那么就证明它是扬声器正极。所以当有英文不明白的时候，可以将它们拆开后再进行理解，请大家灵活运用。 第二节主板元件位置图 一、元件编号 每一个元件在主板元件位置图中，都有一个唯一的编号。这个编号由英文字母和数字共同组成。编号规则可以分成以下几类： 芯片类：以U 为开头，如CPU U101 接口类：以J 为开头，如键盘接口J1202 三极管类：以Q 为开头，如三极管Q1206 二级管类：以D 为开头，如二极管D1102 晶振类：以X 为开头，如26M 晶体X901 电阻类：以R 或VR（压敏电阻）为开头，如电阻R32 VR211
简单手机电路图.txt我自横刀向天笑，笑完我就去睡觉。你的手机比话费还便宜。路漫漫其修远兮，不如我们打的吧。 1、方框图： 利用方块形式粗略概述手机的结构与工作原理，方便初学者掌握手机的结构与工作原理，初学者读懂电原理图打下基础 2、整机电原理图： 利用电子元件符号清楚表示手机中各元器件的连接和工作原理，方便维修时分析电路原理及故障 3、元件排列图： 利用元件编号在板位图上标明元件所在方便维修时寻找元件在机板上的位置。 4、彩图： 即手机照片，方便维修时对照机板元件缺损、错位 二、手机电路图的读解原则： 1、读图前先要打好电子基础，熟悉各种电子元件符号、特性和用途；电子元件在电路中的接法 2、先读懂方框图，大概了解本机的结构（如用哪种电源结构、哪种时钟电路）；然后按所学的原理去分析原理图。 3、读图时应先弄懂直流供电电路，后弄懂交流信号通路。 4、手机电路图是有规律的，一般电源居左下；控制居右下。左射频右逻辑；上收下发中本振。 三、手机电路图的读解方法： 1、电源电路读图要点： 1）、先了解本机属哪种电源结构（分三种）;以电源集成块为核心。 2）、从尾插或电池脚开始，找出电池电压（VBATT、B+）输入线；电池电压一般直接供到电源集成块、充电集成块、功放、背光灯、振铃、振动等电路；也可从上述电路往回找。 3）、在电源集成块、键盘、内联座处找到开机触发线（ON/OFF或标有开关符号）。 4）、在电源集成块上找出各路电压输出线（包括电压走向、电压值多少、是恒定的还是跳变的、在哪个元件上可测到该电压）。 1）VDD——逻辑电压给CPU、字库、暂存等电路（1.8V/2.8V） 2）SYN-VCC（XVCC）时钟电压，使13M电路工作（3.8V） 3）AVCC——音频电压(2.8V) 4）VREF—中频电压(2V跳变) 5）3VTX—发射电压(3V跳变) 6）SYN-VCC—频合电压 7）VRTC—实时时钟电压 8)SIM-CC—SIM电路电压（3V/5V跳变） 9）RST（PURX）——复位信号（2.8V） 4）、在CPU与电源集成块间找到开机维持线（WD-CP、WATCCH G）。 5）、从键盘、电源集成块旁边的开关符号到CPU找到关机检测线。 2）、充电电路读图要点： 1）、以电源集成块或充电集成块为核心，找到充电电路。 2）、从充电接口（尾插）到电源集成块或充电出外电输入线 3）、从外电输入线（DC-IN）9到CPU（或电源）找到充电检测线（CHECK）。 4）、从CPU（或电源）到充电集成块找到充电开关控制线（CHARG-ON）。 5）、从充电集成块（或电源）到电池脚（VBATT）找到充电压输出线。