场致发射显微镜(FEM)

场发射扫描电镜工作原理
场发射扫描电镜（FE-SEM，Field Emission Scanning Electron Microscope）工作原理如下：
1. 电子发射：FE-SEM使用一个称为电子枪的器件产生高能电
子束。

电子枪包含一个钨丝或碳纳米管的尖端，通过加热尖端，电子从尖端发射出来。

2. 调制和聚焦：电子束经过一系列的电场调制和聚焦透镜，以使电子束具有足够的能量和焦点来进行扫描。

3. 扫描和信号采集：电子束被聚焦到一个非常小的尖端，称为扫描线圈。

扫描线圈通过控制电子束的位置和速度，将电子束在样品表面上进行快速的扫描。

当电子束与样品表面相互作用时，会有多种信号产生，如二次电子、反射电子、特征X射
线等。

4. 信号检测：上述信号被检测器捕获，并由电子光学系统将其转换成图像或谱图。

典型的信号检测器包括二次电子探测器、透射电子探测器、X射线能谱仪等。

5. 数据显示和处理：捕获的信号通过计算机进行处理和显示，生成高分辨率的扫描电子显微图像。

计算机还可以对图像进行后期处理，如增强、标记、量化等。

总的来说，FE-SEM利用电子束的显微特性来对样品进行高分
辨率的表面观察，并可获取丰富的样品性质信息。

扫描隧道显微镜（STM）的原理及其在纳米材料研究中的应用引言透射电子显微镜在观察物质的整体结构方面是很有用的，但在表面结构的分析上却较困难，这是因为透射电子显微镜是由高能电透过样品来获得信息的，反映的是样品物质的内部信息。

扫描电子显微镜（SEM）虽然能揭示一定的表面情况，但由于入射电子总具有一定能量，会穿入样品内部，因此分析的所谓“表面”总在一定深度上，而且分辨率也受到很大限制。

场发射电子显微镜（FEM）和场离子显微镜（FIM）虽然能很好地用于表面研究，但是样品必须特殊制备，只能置于很细的针尖上，并且样品还需能承受高强电场，这样就使它的应用范围受到了限制。

扫描隧道电子显微镜（STM）的工作原理完全不同，它不是通过电子束作用于样品（如透射和扫描电子显微镜）来获得关于样品物质的信息，也不是通过高电场使样品中的电子获得大于脱出功的能量而形成的发射电流成像（如场发射电子显微镜），并以此来研究样品物质，它是通过探测样品表面的隧道电流来成象，从而对样品表面进行研究。

STM技术的最大优势在于可获得原子级的分辨率，通常它的分辨率在平行于表面的方向可达0.1纳米，在垂直于表面的方向可达0.01纳米，此外，STM还可实时地获得材料表面实空间的三维图像；可以观察单个原子层的局部表面结构，而不是整个表面的平均性质；配合扫描隧道谱STS可以得到有关表面电子结构的信息，例如表面不同层次的态密度、表面电子势阱等。

在STM之后衍生出了原子力显微镜、磁力显微镜、近场光学显微镜等一系列新型非接触表面探针技术显微镜，使探针显微镜技术日趋完善，并在纳米科技领域中得到越来越广泛的应用。

关键词：扫描隧道显微镜、量子隧道效应、纳米材料一、扫描隧道显微镜的介绍扫描隧道电子显微镜(scanningtunnelingmicroscope，STM)是一种利用量子理论中的隧道效应探测物质表面结构的仪器，利用电子在原子间的量子隧穿效应，将物质表面原子的排列状态转换为图像信息的。

第9讲静电屏蔽电像法本讲提纲1.静电感应现象2.静电屏蔽3.电像法以及应用本讲对等效思维运用较多，思考的时候概念转化很快。

部分不适的同学可以先只关注物理现象以及原理的解释，对于负责的运算大家可以根据自己的兴趣尽力跟进老师的讲解，不妨把部分难题当作对自己能力极限的挑战。

知识模块引入：电场中的导体把一块不带电的导体放到电场周围，这个导体就会感应出电荷。

这个现象不难去理解，一般用电场对电荷的力就能解释。

静电感应:导体内自由电子在外电场的作用下定向移动,重新分布的现象.本讲研究的是这个现象的定量规律。

如图演示的是在外电场下金属内部自由电子从移动，到最后稳定分布的过程。

知识点睛一.静电平衡:导体中(包括表面)没有电荷的定向移动的状态.由于感应电荷形成新的电场，最终导致金属内部合场强降为零，静电感应现象才达到了稳定，我们不妨称之为静电平衡。

1.导体内部的场强处处为零.2.整个导体是个等势体,导体的表面是等势面.3.净电荷分布在导体的外表面.4.在导体表面附近,电场线一定与表面垂直.如图是一般形状的金属放入电场后的影响二．静电屏蔽导体壳（网罩）不接地时，可以实现外部对内部的屏蔽，但不能实现内部对外部的屏蔽；导体壳（网罩）接地后，既可实现外部对内部的屏蔽，也可实现内部对外部的屏蔽。

如下图的演示试验，当导体放到静电计周围，并用金属球壳把静电计包起来后，静电计的指针是不偏转的。

如图是静电屏蔽掉超高压的试验示意，在高压电线上工作的工人穿的也是用金属制作的衣服，屏蔽电线周围的强电场。

下面列了另外的一些关于静电屏蔽的应用，具体内容请同学们课后自己查阅资料或者咨询老师。

1.电子仪器，比如示波器的接线都是这样的屏蔽线；2.外的天线；3.电视信号线，外面就有一层金属丝，就为了静电屏蔽，使信号不受干扰；4.务区怕被人打手机，又不能关机，找个金属盒子装进去，就变成了“您拨打的用户不在服务区”；例题精讲【例1】如图所示，把一个带正电的小球放人原来不带电的金属空腔球壳内，其结果可能是（）A ．只有球壳外表面带正电。

1表面、界面的定义与理解：表界面是由一个相过渡到另一相的过渡区域。

习惯上把固－气、液－气的过渡区域称为表面，而把固－液、液－液、固－固的过渡区域称为界面。

根据物质的聚集态，表界面通常可以分为以下五类：固－气；液－气；固－液；液－液；固－固；物理表面包括：理想表面、清洁表面、吸附表面表面是一个抽象的概念，实际常把无厚度的抽象表面叫数学表面，把厚度在几个原子层内的表面叫作物理表面，而把我们常说实际的固体表面叫工程表面。

2 理想表面理论前提：①不考虑晶体内部周期性势场在晶体表面中断的影响；②不考虑表面原子的热运动、热扩散、热缺陷等；③不考虑外界对表面的物理-化学作用等；④认为体内原子的位置与结构是无限周期性的，则表面原子的位置与结构是半无限的，与体内完全一样。

3何为清洁表面？清洁表面获得方法？指不存在任何污染的化学春表面，即不存在吸附、催化反应或杂质扩散等一系列物理、化学效应的表面。

获得清洁表面的几种方法: ①在获得超高真空的同时获得清洁的表面。

②用简单的加热方法去除表面的沾污。

③在化学气氛中加热去除那些通过简单加热不能清除的化学吸附沾污。

④对于较顽固的沾污，可以利用惰性气体离子（如Ar+、Ne+）轰击表面而有效地清除污染。

⑤对于一些晶体，可以采用沿特定的晶面自然解理而得到清洁表面。

⑥在适当的基片上通过真空蒸发法获得预想的单晶和多晶薄膜，作为研究对象的清洁表面。

4 根据原子结构的不同清洁表面分哪几种？图示说明（PPT）弛豫表面：指表面层之间以及表面和体内原子层之间的垂直间距d s和体内原子层间距d0相比有所膨胀和压缩的现象。

可能涉及几个原子层。

重构表面：指表面原子层在水平方向上的周期性不同于体内，但在垂直方向上的层间间距d0与体内相同。

台阶结构：表面不是平面，由规则或不规则台阶组成。

由于晶体内部缺陷的存在等因素，使晶体内部应力场分布不均匀，加上在解理晶体对外力情况环境的影响，晶体的解理面常常不能严格地沿所要求的晶面解理，而是伴随着相邻的倾斜晶面的开裂，形成层状的解理表面。

Instructions f or o perating J EOL J SM-­‐7500FA a nalytical field e mission s canning e lectron m icroscope a t Nanomicroscopy C enterVersion 2.1 (April 2011)Juuso K orhonen (***********************)Latest v ersion o f t his d ocument c an a lways b e d ownloaded f rom:k.fi/en/instruments/sem/jsm-­‐7500fa/SEM-­‐instructions.pdfOfficial i nformationNew u ser t rainingInexperienced u sers h ave a c ouple o f o ptions, l isted b elow i n t he o rder o f preference.1.Ask f or t raining f rom t he m ost e xperienced S EM u ser o f y ourresearch g roup.2.Attend t o t he c ourses T fy-­‐125.4313 a nd T fy-­‐125.4314 M icroscopyof n anomaterials (5+5 c r). T hey a re l ectured e ach s pring b y P rof.Janne R uokolainen.3.Ask o ne o f t he a dministrators t o a rrange a t raining s ession.a.Small g roups o f 2-­‐3 p eople a re p referred f or t he t rainings.Allow s ome t ime t o g ather e nough p eople f or t he g roup.b.Training i s d one u sing a p ractice s ample a nd p ersonalsamples a re u sually n ot i maged.Experienced u sers c an c ontact o ne o f t he a dministrators f or a s hort introduction t o t he e quipment.Every n ew u ser h as t o b e a pproved b y o ne o f t he a dministrators b efore t hey are a llowed t o u se t he S EM o n t heir o wn. T he a dministrator k eeps a s hort (15-­‐30 m in) s ession w here t he e ssential s kills o f t he u ser a re c hecked. User a pplicationUser a pplication h as t o b e f illed i n o rder t o g ain r eservation a ccess t o a ny o f the N MC e quipment. T he f orm c an b e f ound f romk.fi/en/documents/nmc_user_application_form.pdf a nd i t i s returned t o o ne o f t he a dministrators f or a pproval.PricingBilling i s d one u sing t he c urrent N MC p rice l ist. C ontact P rof. J anne Ruokolainen f or t he m ost c urrent l ist. P lease n ote t hat i ndividual t raining given b y t he a dministrators w ill a lso b e c harged.Precautions – r ead c arefully•Always c heck t he l iquid n itrogen l evel a nd f ill i f n ecessary.o First u ser o f t he d ay a lways f ills t he t ank.•Keep a ll p arts c lean a nd c lean t hem i f n ecessary w ith e thanol.o Wear g loves w hen h andling h olders.•Fill t he l og b ook o n t he c omputer.o Mark a ny s trange b ehavior o r p roblems t o t he l og b ook.•If s omething i s m issing f rom t he S EM o r f rom t he s ample p reparation room (e.g. g loves, e thanol, h olders, c arbon t ape), p lease i nform o ne o fthe a dministrators (send e mail o r c all).•Use o nly f eatures y ou a re t rained t o u se. F or e xample, d o n ot u se EDS o r R BEI i f y ou d on’t k now h ow t o o perate t hem s afely.•Use o f U SB s ticks i s s trictly p rohibited d ue t o s ecurity i ssues a nd hardware i ncompatibility.•Stay c alm a nd u se y our c ommon s ense.•Contact a dministrators i f y ou a re i n d oubt. C ontact i nformation i s found o n t he l ast p age o f t hese i nstructions.Quick s tartup p rocedure1.Turn o n b oth m onitors a nd c heck t hat S EM s oftware a nd u sage l og(Excel) a re r unning. S tart t hem i f n ecessary. L og i n a s G uest (nopassword).2.Check t he l iquid n itrogen l evel a nd f ill i f n ecessary. T he f irst u serof t he d ay a lways f ills t he t ank.3.Fill t he u sage l og:a.Date, s tart t ime (and e nd t ime).b.Your n ame (and t he n ame o f y our h ost i f y ou d o n ot h avereservation p ermissions).c.Vacuum l evels b efore s tarting.d.Amount o f f illed l iquid n itrogen (write “0” i f y ou o nlychecked t he l evel).e.Write n otes a nd c omments t o t he l ast f ield i s n ecessary.f.Save t he f ile (Ctrl-­‐S).4.Prepare y our s ample.5.Insert s ample i nto m icroscope:a.Press E xchange p osition.b.Press a nd h old V ENT f or c a. 1 s ec. O pen s ecuring l atch. W ait.c.Open c hamber a nd i nsert h older a long t he d irection o f t hearrows.d.Close c hamber.e.Press a nd h old E VAC f or c a. 1 s ec. W ait u ntil b linking s tops.f.Operate t he r od t o m ove t he s ample t o t he s tage. I f y ou’re n otabsolutely c ertain h ow t o d o t his, r ead t he d etailedinstructions!g.Take o ut t he r od.6.Wait u ntil v acuum l evel r eaches l ess t han 5⋅10-­‐4 P a.7.Set E mission c urrent t o 10 μA.8.Select A cceleration v oltage.9.Press O bservation O N.Shutdown p rocedure1.Press O bservation O FF t o t urn o ff a cceleration v oltage.2.Press E xchange p osition.3.Take o ut h older u sing t he r od.4.Press a nd h old V ENT f or c a. 1 s ec. O pen s ecuring l atch. W ait.5.Open c hamber a nd t ake o ut t he h older.6.Close c hamber.7.Press a nd h old E VAC f or c a. 1 s ec.8.Mark e nding t ime a nd o bservations t o U sage l og a nd s ave f ile (Ctrl-­‐S).9.Set S EM M onitor s oftware t o n ormal s ettings:a.Exchange p osition p ressed (green).b.Mode: S EMc.Magnification: m inimum f or b oth S EM a nd L Md.Probe c urrent: 810.Turn o ff s pecial f eatures y ou h ave u sed: I mage r otation, d ynamicfocus, e tc.11.If y ou m ade a ny c hanges i n t he O peration S ettings m enu, c hangethem t o n ormal v alues (scan s peeds, i mage f unction, e tc.).12.Clean t he h olders w ith e thanol i f n ecessary.13.Clean t ables. I f y ou w ant t o s tore y our s amples, m ark t hem w ith y ourname a nd p ut t hem o nto a s helf. T hings l eft o n t he t able a re t hrowninto t he t rash.14.Transfer y our i mages f rom t he s mall c omputer o n t he b ack t able.You c an f ind y our f iles a t t he n etwork d rive c alled H arley.e U SB s tick, S SH, e mail, o r b urn a C D.b.The f iles c annot b e t ransferred d irectly f rom t he S EMcomputer d ue t o s ecurity r easons.15.Turn o ff m onitors. D o n ot l og o ut f rom t he s oftware o r c lose t heExcel l og b ook.Changing s ample1.Press O bservation O FF t o t urn o ff a cceleration v oltage.2.Press E xchange P osition t o m ove t he s tage t o c orrect p osition.3.Take s ample o ut b y o perating t he r od.4.Press a nd h old V ENT f or c a. 1 s ec. t o f lush c hamber a nd o pen l atch.Wait.5.Open c hamber a nd t ake o ut s ample (pull a long t he a rrows, n ot u p).6.Change s ample a nd i nsert h older a long t he a rrows.7.Close c hamber a nd s ecure w ith l atch.8.Press a nd h old E VAC f or c a. 1 s ec. W ait u ntil b linking s tops.9.Insert s ample b y o perating t he r od. T ake o ut r od.10.Wait u ntil c hamber v acuum r eaches 5⋅10-­‐4 P a b efore t urning o nacceleration v oltage.Special f eaturesThis i s o nly a q uick r eference. S pecial t raining i s r equired t o u se R BEI o r E DS, because o f s afety i ssues.Infrared c ameraYou c an s ee i nside t he c hamber u sing t he i nfrared c amera.1.Switch c amera o n f rom t he b utton o n t he t able.2.From S EM s oftware s elect N avigator -­‐> I nfrared c amera3.Turn c amera o ff w hen u sing R BEI o r E DS.Probe c urrent m eterProbe c urrent m eter c an b e u sed t o c heck t he c urrent g oing t o t he s ample. I t is m ost i mportant i n E DS a nalysis.1.Insert t he d etector b y c hecking P CD f rom t he b ottom r ight c orner o fSEM s oftware.2.Take o ut d etector a fter y ou h ave r ead t he c urrent f rom t he S EMsoftware.Retractable b ackscattering d etector (RBEI)Backscattering d etector i s u sed t o d istinguish b etween e lements o n t he sample.1.Set w orking d istance t o 8 m m o r m ore.a.Inserting R BEI w ith l ess t han 8 m m b etween t he s ample a ndthe o bjective l ens w ill r esult i n s erious d amage.2.Turn o ff i nfrared c amera.3.Insert d etector b y c hecking R BEI f rom t he b ottom r ight c orner o f t heSEM s oftware.4.Select C OMPO o r T OPO f or i mage m ode (same m enu a s S EM a nd L M)and u ser a s low s canning s peed f or o bservation.X-­‐ray a nalysis (EDS)This g uide i s n ot a dequate f or p roper o peration o f E DS, b ut i s o nly a q uick reference f or t rained u sers.1.Set w orking d istance t o e xactly 8 m m.a.Focus w ith Z h eight u sing t he r ing o f t he s croll w heel i nsteadof F OCUS.2.Insert R BEI.3.Turn o n b ias v oltage b y c licking t he l ightning i ndicator.a.Wait u ntil c ount r ate s tabilizes.4.Select A nalysis f rom t he r ight s ide o f S EM s oftware.5.Click D T (dead t ime) a nd s elect T4 f rom t he l ist.6.Adjust p robe c urrent s o D T b ecomes g reen (around 20-­‐30 %) a ndcount r ate i s c a. 2000-­‐3000 c ps.7.Take s pectra, l ine s can, o r m apping u sing t he a ppropriate b uttons.8.When a sked a bout s aving t o a n etwork d rive, s elect O K.9.Save t he a nalysis b efore e xiting a nalysis m ode i n o rder t o b e a ble t oreturn t o t he a nalysis l ater.a.Exporting o nly s aves t he i mage a nd y ou c annot r eturn t omake m ore a nalysis o n t he d ata.10.When y ou a re f inished w ith a nalysis, t urn o ff t he b ias v oltage a ndtake o ut R BEI.Saving E DS s pectraIf y ou w ant t o b e a ble t o p lot y our E DS s pectrum, s elect E xport a nd t hen select M SA f ile. I t w ill s ave t he s pectrum i n a c ompatible f ile f or u se i n O rigin, Excel, o r s ome o ther p lotting p rogram.Detailed i nstructionsOperating t he r od (sample e xchange m echanism)This p rocedure d escribes h ow t o u se t he s ample e xchange m echanism i norder t o e ither r emove o r i nsert a s ample h older i nto/from t he m icroscope.Read t his s ection c ompletely t hrough b efore p roceeding a nd m ake s ure t hatyou u nderstand e very s tep.Precondition: T he e xchange c hamber i s i n v acuum a nd t he d oor s eparatingit f rom t he m icroscope i s o pen. C onfirm t hat E VAC l ight i s l it a nd n otblinking. D epending o n w hether y ou a re i nserting o r t aking o ut a s ample, t heholder m ight b e i n t he e xchange c ompartment (HLDR l ight i s o ff) o r i nsidethe m icroscope (HLDR l ight i s o n).See t he v ideo o n t he c omputer d esktop f or a d emonstration. U PDATE: T hefigures a re f rom a n o ld v ersion o f r od.1.Push t he b ar i nside t he m icroscope b y f ollowing t he p rocedure:a.Lower t he r od t o h orizontal l evel, w hile l ightly h olding i tback.b.Let t he r od b e p ulled i n s lowly.c.Push t he b ar g ently a ll t he w ay i nside u ntil i t s tops (d).•There i s a l ittle r esistance a t t he f inal c ouple o fcentimeters.•The s ample s hould b e n ow e ither r eleased f romthe b ar o r a ttached t o i t (depending o n w hetheryou a re i nserting o r r emoving t he h older).•If y ou h ave n ot p ushed t he s ample a ll t he w ayinside a nd s tart t o p ull b ackwards t here i s adanger t hat t he s ample h older w ill f all t o t hebottom t he s ample c ompartment. I f t his h appens,the w hole s ample c ompartment h as t o b e o pened.Contact S EM a dministrators i n t his c ase.2.Pull t he b ar o ut f rom t he m icroscope u sing t he f ollowingprocedure:a.Pull t he b ar o ut a s f ar a s i t c omes (e).•The t wo a rrows o n t he h older s hould a lign w iththe p ipe e nd.•If y ou h ave n ot p ulled f ar e nough, t he r od m ightbe d amaged d uring t he l ift.b.Lift t he r od u pwards t o v ertical.•Now y ou s hould e ither h ave t he s ample i nside t hemicroscope o r i n t he e xchange c ompartment a ndthe e xchange c ompartment i s i n v acuum.Opening t he s ample e xchange c ompartmentThe f ollowing p rocedure d escribes h ow t o b ring t he e xchangecompartment t o a tmospheric p ressure.Precondition: T here i s n o s ample i nside t he m icroscope o r i t h as b eenbrought t o t he e xchange c ompartment, a nd t he e xchange c ompartment i sin v acuum. F irst c heck t hat H LDR l ight i s o ff o n t he s ample e xchangecompartment (i.e. t here i s n o s ample i nside t he s ample c ompartment).Figure. S ample e xchange r od1.Pressurize t he e xchange c ompartment:a.Press a nd h old (for a bout 1 s econd) t he V ENT b utton o n t heexchange c ompartment.i.The b utton s tarts t o b link a nd y ou h ear s ome s ounds.ii.In a f ew s econds, t he d oor b etween t he e xchangecompartment a nd t he s ample c ompartment c loses.You c an o bserve t his b y e ar a nd b y l ooking a t t hebottom r ight c orner o f t he S EM M onitor.2.Open t he l atch a s s oon a s y ou h ear t he c lick.3.Open t he e xchange c ompartment d oor (it s hould o pen a lmost b yitself).a.You d o n ot n eed t o w ait u ntil t he p umping h as s topped.b.The c ompartment w ill c ontinue p urging f or a f ixed a mount o ftime. Y ou d o n ot h ave t o w ait u ntil i t s tops a nd y ou c anevacuate i t a s s oon a s y ou l ike.4.Now y ou h ave t he s ample c ompartment o pen a nd r eady f orloading/unloading t he s ample h older.Inserting a s amplePrecondition: T here i s n o s ample i nside t he s pecimen c hamber a nd exchange c ompartment i s i n v acuum. F irst c heck t hat H LDR l ight i s o ff o n the e xchange c ompartment (i.e. t here i s n o s ample i nside).1.Move t he s tage t o e xchange p osition:a.Click E xchange P osition o n t he S EM M onitor.i.If b utton i s n ot v isible, c lick "Specimen" f rom t herightmost e dge o f S EM M onitor.ii.Make s ure t hat E XCH P OSN i s l it o n t he e xchangecompartment, b efore p roceeding.2.Bring t he e xchange c ompartment t o a tmospheric p ressure b yfollowing p rocedure i n s ection “Opening t he s ample e xchangecompartment”. Q uick n otes:a.Press a nd h old V ENT f or c a. 1 s ec.b.Open l atch. W ait.c.Open c hamber d oor.3.Put o n g loves i f y ou d o n ot h ave t hem a lready o n.a.Parts t hat a re i n c ontact w ith t he v acuum s hould b e k eptabsolutely c lean. I f y ou h ave t ouched s ome p art, c lean t he p artwith e thanol (not a cetone).4.Insert h older t o t he s pecimen c huck:a.Slide t he s pecimen h older i nto t he s pecimen c huck a long t hearrow d irection o n t he s pecimen h older.5.Check t hat t he O-­‐ring s eal o n t he d oor i s O K a nd w ipe i t w ith a c leanglove i f n eeded t o g et r id o f a ny d ust.a.If t he r ing i s r eally d irty, w ipe i t w ith e thanol o r i sopropanol(do n ot u se a cetone o r m ethanol).6.Close t he c hamber d oor a nd s ecure i t w ith t he l atch.7.Evacuate t he c ompartment b y p ressing a nd h olding E VAC (forabout 1 s econd). T he l ight w ill s tart b linking.a.Wait u ntil t he l ight s tops b linking a nd t he d oor s eparatingthe e xchange c ompartment i s c losed. Y ou c an o bserve t hisfrom t he b ottom r ight p art o f t he S EM M onitor.8.Insert t he s ample h older i nside t he m icroscopea.Refer t o s ection “Operating t he r od” i f i n d oubt.9.A p opup w indow s hould a ppear o n t he S EM M onitor. N ow s elect t heappropriate h older a nd s et t he o ffset v alue.a.If p opup d oes n ot a ppear, t ake o ut t he h older a nd i nsert i tagain.10.Wait u ntil t he v acuum l evel r eaches 9.6·10-­‐5 P a (if t hat i s n otpossible, w ait a t l east u ntil 5·10-­‐4 P a).Taking o ut s amplePrecondition: T here i s a s ample i nside t he m icroscope a nd e xchange compartment i s i n v acuum. F irst c heck t hat H LDR l ight i s o n o n t he s ample exchange c ompartment (i.e. t here i s a s ample i nside) a nd E VAC l ight i s o n and n ot b linking.1.Click O bservation O FF t o t urn o ff a cceleration v oltage.2.Click E xchange P osition t o m ove t he s ample h older t o t he e xchangeposition.a.Make s ure t hat E XCH P OSN i s l it o n t he e xchangecompartment b efore p roceeding.3.Bring t he s ample t o t he e xchange c ompartment b y o perating t herod.a.Refer t o s ection “Operating t he r od” i f y ou a re n ot a bsolutelycertain h ow t o d o t his.4.Pressurize t he e xchange c ompartment:a.Press a nd h old V ENT f or c a. 1 s ec u ntil i t s tarts t o b link.b.Open s ecuring l atch. W ait.c.Open c hamber d oor.5.Now y ou h ave t he s ample c ompartment o pen a nd y ou a re r eady t akeout y our s ample. I f y ou a re d one w ith t he i maging, j ust c lose t heexchange c hamber a nd e vacuate i t o therwise c ontinue w ith i nsertinga n ew s ample. D o n ot l eave t he c hamber o pen f or a l ong p eriod o ftime, b ut e vacuate i t i f n eeded.Sample h oldersSample h olders c onsist o f a b ase p art a nd a n a dapter p art (show o n t he f igure right). T here a re t hree d ifferent a dapters f or d ifferent s pecimen s tubs s hown in t he f igure b elow (a, b , c , d ).The m ost b asic h olders a re t he 12.5 m m (b-­‐1) a nd 25 m m (c-­‐1) a luminum “JEOL” s tubs . T hey s hould b e u sed w henever p ossible. S tubs s hould a lways b e available a t t he s ample p reparation r oom, b ut y ou c an a lso o rder y our o wn ones e .g. f rom E MS (order n umbers 75730, a nd 75700). T he u se o f r egular holders i s i ncluded i n t he o peration p rice o f t he m icroscope.Also “mini-­‐stubs” a re a vailable f or u se w ith a p rovided a dapter. T hey a re preferred f or s mall s amples. T hey c an b e o rdered f rom T ed P ella (order numbers 16180, a nd 16181).For s pecial o ccasions, a H itachi a dapter (a) c an b e u sed. S pecial c are m ust b e taken w hen u sing t hese h olders, b ecause t hey l ack s ome s afety f eatures. Ask a dministrators, i f y ou h ave s pecial r equests f or h olders. T here a re a lso different k inds o f c ross-­‐section h olders a vailable. A sk t he a dministrators f or more i nformation.Attaching a dapter t o b ase p arta) Make s ure t hat p arts a re n ot d irty, c lean i f n ecessary. b) Place a dapter o n t he b ase p art.c) Tighten s crew o n t he b ase p art l ightly.Figure. A ttaching a dapter t o base p art.Figure. 12.5 m m a nd 25 m m "JEOL" stubs.Figure. "Mini-­‐stubs" a nd 12.5 m m a dapter.Figure. C ross-­‐section holders.Sample h eightAlign t he t op o f t he s ample w ith t he g roove i nside t he J EOL a dapter p art. U se the s crew o n b ottom t o r aise o f l ower t he s ample. W hen u sing a nother holder, m ake s ure t hat h eight f rom t able t op l evel i s e xactly 25 m m.CoatingFor n on-­‐conductive s amples a c oating i s u sually n eeded f or o bservation i n SEM. T his c an b e e asily p erformed b y u sing s putter c oating o f g old, p latinum, or g old-­‐palladium. T here i s a s putter c oater a t N MC, w hich c an b e u sed f or this p urpose. R esolution l imiting f actor i s t he g rain s ize, w hich i s u sually 5-­‐20 nm d epending o n t he c onditions o f s puttering.Also c arbon c oating c an b e u sed t o m ake s amples c onductive. I t i s a nappealing m ethod, w hen d oing X -­‐ray a nalysis. I t c reates a v ery u niform l ayer without n oticeable grains.Figure. A lign t op o f stub w ith t he g roove on t he s ample holder.Basic m icroscope o perationBasic c onceptsWorking d istance a nd Z v alueWorking d istance (WD) v alue s ets t he e ffective f ocal l ength o f t he o bjective lens.Z h eight v alue s ets t he d istance o f t he (supposed) s urface l evel o f t he s ample from t he o bjective l ens.These t wo v alues a re e qual, w hen t op o f s ample i s a ligned w ith t he t op o f the h older (ie. 25 m m h igh f rom t able l evel, s ee f igure). W D > Z, i f y our sample i s l ower t han t he c orrect l evel a nd v ice v ersa. I f W D < Z y ou n eed t o set t he S ample O ffset v alue a ccordingly.Sample o ffsetThe h eight o f t he t op l evel o f t he s ample m easured f rom t able t op l evel should b e e xactly 25 m m. T he s ample c an b e s et a lso 0-­‐4 m m h igher t han t he nominal l evel, b ut t hen t he S ample O ffset v alue h as t o b e s et a fter i nserting sample. I t i s l ocated a t t he b ottom o f t he s ample h older s elect w indow, w hich pops u p a utomatically a fter h older i nsert.Acceleration v oltage, e mission c urrent, p robe c urrent…The f irst t hing t o t hink a bout w hen s tarting i maging i s t he s election o f acceleration v oltage. T he c hoice d epends o n t he t ype o f t he s ample. S ee table b elow f or s ome e xamples.Sample Observation c ondition NotesGold p articles o n conductive s urface 5-­‐30 k V, p robe c urrent a t c a. 10, working d istance 1.5-­‐8 m mCoated p orous polymer 1-­‐5 k V, p robe c urrent 6-­‐10, w orking distance 4.5-­‐8 m mUncoated p olymer 0.5-­‐1 k V, p robe c urrent < 8, g entlebeam m ode, w orking d istance c a. 8mmCoated b iological sample 1-­‐5 k V, p robe c urrent c a. 10, w orking distance 4.5-­‐25 m m d epending o n feature s izeUncoated p aper 1-­‐2 k V, g entle b eam (GB-­‐L) m ode,working d istance 4.5 m m, p robecurrent 6-­‐10.Coated p aper 5 k V, w orking d istance 4.5-­‐25 m m,probe c urrent c a. 10X-­‐ray a nalysis o f conductive s ample 15-­‐30 k V, w orking d istance e xactly 8mm, h igh p robe c urrentRetractable B EIdetector i nsertedX-­‐ray a nalysis o f poorly c onductive sample 5 k V, w orking d istance e xactly 8 m m,probe c urrent a s h igh a s p ossibleRetractable B EIdetector i nsertedThe e mission c urrent i s t he c urrent d rawn f rom t he e mitter. S et i t a lways t o 10 μA. Figure. S ample height s hould b e exactly 25 m m measured f rom t able top l evel.Probe c urrent i s t he c urrent d irected a t t he s ample. H igher v alues g ive better s ignal t o n oise r atio, b ut c ause m ore c harging a rtefacts i n p oorly conducting s amples. V alue o f 8-­‐10 i s u sually a g ood c hoice.AligningUsually t he m icroscope i s a ligned w ell e nough f or m icrometer s cale operation. I n t his c ase, o nly f ocusing i s n ecessary. F or h igher m agnification work, t he e lectron b eam n eeds t o b e a ligned a nd a stigmatism o f t he o bjective lens h as t o b e c orrected.FocusThe f irst l evel o f a ligning i s a lways f ocusing. F ocusing i s d one u sing t he FOCUS k nob o n t he o peration c onsole. C lockwise r otation i s u nder f ocus (weaker l ens) a nd c ounterclockwise i s o ver f ocus (stronger l ens).If p ossible s elect s ome f eature, w hich y ou c an u se i n t he m agnification r ange from c a. 1000 t o 20000.Start f rom a l ow m agnification a nd w hen y ou g et g ood e nough i mage m ove on t o h igher m agnification f or f ocusing. I t t he a lignments a re r eally o ff, y ou might n ot g et a c lear i mage a t a ll.Beam a lignBeam a lign i s a lways d one a t p robe c urrent 8. S elect t he c orrect p robe current v alue f rom t he s oftware.Press A LIGN o n o peration c onsole. T he i mage s tarts t o m ove o n t he s creen. Use t he X a nd Y k nobs t o m inimize t he m ovement. P ress A LIGN O FF (STIG) button w hen i mage h as s topped. R epeat f or m agnifications u p t o c a. 20000. Focus t he i mage w henever n ecessary.Astigmatism c orrectionTo c orrect t he o bjective l ens a stigmatism p ress t he S TIG b utton o n t he operation c onsole (it i s u sually a lready s elected a t t his p oint). M ove o n t o a spherical f eature, w hich y ou a re a ble t o o bserve a t m agnification 10000 o r more.Move t he F OCUS k nob s o t hat y ou g o f rom u nderfocus t o o verfocus a nd b ack several t imes. W hen y ou h ave a stigmatism, t he i mage g ets e longated i n diagonal d irections w hen m oving a round t he f ocal p oint. S elect t he f ocal point w here n o e longation o ccurs.Adjust t he X a nd Y k nobs s o t hat y ou g et t he c learest i mage p ossible. F ocus whenever n ecessary.Other c orrectionsThere a re a lso o ther a lignments, s uch a s s ource a lign, c ondenser l ens astigmator, l ow m agnification c enter, a nd s tigmator c enter c orrections. These v alues s hould n ot u sually b e c hanged a nd t heir u se i s n ot d escribed here.Problems a nd t roubleshootingAnswers t o c ommon p roblemsI w ant t o u se U SB s tick t o t ransfer m y f iles!You c an t ransfer y our f iles t o a U SB s tick f rom t he s mall c omputer a t t he b ack wall. Y ou’ll f ind y our f iles u nder t he n etwork d rive H arley.Help! T here i s n o i mage.Follow t he c hecklist t o f ind t he c ause:1.Are y our Z a nd W D v alues t he s ame? I f n ot p ress W D t o s et c orrectdistance.2.What d etector a re y ou u sing? I f W D<8 m m y ou u sually d o n ot g etimage w ith L EI d etector; a nd i f W D>8 m m S EI g ives o nly s tatic n oise.LM m ode s hould w ork f ine i n t his c ase.3.What i s y our p robe c urrent v alue? I f i t i s l ow, t ry i ncreasing i t.4.If n one o f t he a bove i s t rue, t ry r esetting a lignment. G o t o A lignmentpanel a nd c lick R eset A ll.a.In a r eally b ad c ase t he s ource a lignment h as g one b ad.Contact a n a dministrator t o a lign i t.If t here i s n o i mage w hen s tarting o perationFirst, p ress A CB (auto c ontrast & b rightness). I f y ou e ven s ee s ome s tatic noise, y ou o nly n eed t o f ind t he c orrect f ocal p oint. S ee p revious s ection.In c ase y ou h ave c ompletely b lack s creen w hen y ou s tart i maging, f ollow t he list u ntil y ou h ave i mage.1.Restart o f S EM s oftware:a.File-­‐>Exit t o g o t o l ogin s creen.b.Close l ogin s creen f rom E xit b utton.c.Wait o ne m inute.d.Start S EM_Monitor s oftware.e.Log i n a s G uest.2.Restart c omputer:a.Close S EM s oftware.b.Save E xcel l og b ook a nd e xit.c.Restart W indows.d.Start S EM s oftware a nd E xcel l og b ook.3.Restart o peration c onsole:a.Read i nstructions b elow.If v acuum b reaks d uring s ample e xchangeVacuum u sually b reaks i f t he l ever i s p ushed o r t wisted d uring t he s ample insertion. T he c omputer w ill r aise a m aintenance w indow s howing e rror messages. T he m icroscope w ill a utomatically s hut d ownsome p arts a nd t he v acuum p umps h ave t o b e r estarted. B ring t he microscope b ack t o i ts n ormal c ondition b efore p roceeding. F or e xample, lift t he r od b ack t o i ts u pright p osition.1.Locate t he t wo V AC S W b uttons b elow t he t able. T here a re a lso M AINSW b uttons, b ut d o n ot t ouch t hem.2.Shut d own v acuum p umps b y p ressing V AC O FF (0=OFF, 1=ON)button. T he p umps s hould n ow s top, i f t hey w ere n ot s hut d ownalready.3.Wait a m oment a nd r estart p umps b y p ushing V AC O N b utton.a.There i s a 20 m in t imer f or s tarting t he p umps s o y ou w illhave t o w ait a t l east 20 m inutes b efore p roceeding.4.After a ll o f t he e rror m essages h ave d isappeared f rom t he d isplay,you c an c ontinue o perating.Turning o ff c omputer1.Log o ut f rom t he S EM s oftware (File-­‐>Exit).2.Save t he E xcel l og b ook (File-­‐>Save o r C trl-­‐S).3.Close t he E xcel l og b ook.4.Select S hutdown f rom S tart m enu.Powering o n c omputer1.Start c omputer f rom t he p ower s witch.2.Log i n a s S EMUser (password: S EMUser).3.Start E xcel l og b ook b y d ouble c licking “SEM U sage L og” o n t he r ightmonitor d esktop.4.Start S EM s oftware b y d ouble c licking S EM_Monitor.5.Log i n a s G uest.Restarting o peration c onsole1.Turn o ff c omputer.2.Press O P S W O FF f rom b elow t he t able.3.Wait c a. 10 s econds.4.Press O P S W O N.5.Turn o f c omputer.6.Wait a c ouple o f m inutes b efore s tarting S EM_Monitor s oftware.。

表界面的分类：气-液；气-固；液-液；液-固；固-固✧表面浓度✧分散度✧表面形貌非均匀性原因：由于固体表面原子的组成、排列、振动状态和体相原子的不同，由于悬挂键导致的化学性质活泼，以及周期性的势场中断导致的表面电子状态差异，固体表面形成很多导致表面形貌非均匀性的元素。

✧位错密度✧表面粗糙度：✧原矢✧米勒指数（miller index）✧晶面间距d hkl✧✧✧表面自由能✧减小表面能的方法✧表面原子重排机理1：表面弛豫作用2：表面相转变3：吸附对纯净底物表面结构的影响层间距的变化；重组的表面结构的变化；吸附原子可以诱导表面重组✧内外表面内表面：多孔或多层材料，孔内或层间的表面比表面积：单位质量材料的表面积；用BET方法测量1.固体表面性质简介固体表面的性质结构特征：不同的位置有不同的性质表面运动：气体分子表面撞击速度；表面扩散系数（爱因斯坦方程）：外延生长原子的运动流程：a沉积/吸附在平台上-deposition；b沉积在原子岛上；c 平台上扩散-diffusion；d脱附-desorption；e成核-nucleation；f交互扩散-interdifusion；g粘附在平台上-attachment；h从平台上脱离-detachment；i：粘附在台阶上化学性质：表面浓度依赖于气体分子撞击速度R相界面（Gibbs界面）表面热力学函数其他类推：S，G，G s比表面自由能与温度的关系; ;Van der Waals and Guggenheim Equation:Where: T c为临界温度；为0Kし的表面张力；固体表面能的理论估算金属表面张力估算；偏析作用来自晶体或固溶体中的杂质或溶质在界面聚集的现象表面偏析公式：正规溶液参数扩散扩散：由热运动引起杂质原子、基质原子或缺陷输运的过程原因：原子或离子分布不均匀，存在浓度梯度，产生定向扩散扩散机理：间隙扩散，空位扩散，环形扩散表面扩散靠吸附原子或平台空位的运动实现。

场离子显微镜张红敏场离子显微镜原理场离子显微镜（FIM）是一种具有高分辨, 高放大倍数且能直接观察固体表面原子的表面研究装置。

它是从场发射显微镜(FEM)发展而来的,1937年E.W Muller开始研究场发射显微镜,用以研究化学吸附和表面扩散等,但分辨率很差所以不能看到单个原子,而将场离子显微镜与飞行时间质谱连接而构成所谓原子探针场离子显微镜（APFIM）, 则既可以直接观察样品表面的原子排列, 又可以鉴别极微区（几个0A）内原子的成分,场离子显微镜已广泛应用于表面科学及材料科学方面的研究。

场离子显微镜将经电化学腐蚀后达到一定曲率半径的针尖样品正对着平板状的荧光屏，为了提高针尖样品的发射稳定性和分辨率, 须将样品冷至液氮、液氢或液氦温度,其次要将镜体内的残余气体抽真空，然后导入He，Ne等稀有气体等或者它们的混合物作为成像气体。

实验时，将针尖加上强正电压，于是以及H2在针尖尖端与萤光屏(接地) 之间就产生放射状的电场。

由于在针尖部分场强很强，由于量子力学的隧道效应, 成像气体原子很容易被离化，即“场离化”，然后, 气体离子就沿着放射状电场加速到达荧光屏, 在荧光屏上产生与表面原子一一对应的辉点。

场离子显微镜的基本原理包括:1.量子力学中电子的隧道效应。

它又称势垒贯穿，是指一个运动的电子遇到一个高于电子能量的势垒，按照经典力学，它是不能越过势垒的，但是按照量子力学，可以解出除了在势垒处的反射外，还有透过势垒的波函数，这表明在势垒的另一边，粒子仍具有一定的概率。

它反映了微观粒子的波动性的存在。

如图1。

2.电学中导体表面电场与其曲率成正比。

即以相同的电压加上相同的导体上，曲率越大,也就是越尖的,导体上电荷越密集，其产生的电场越强。

3.场离化原理。

当气体分子靠近金属或导体样品表面时，强大的正电场改变了气体原子中电荷的分布，气体分子被极化而受电场吸引向针尖飞去。

当气体分子相当靠近具有高电场的表面时，气体分子中电子的位能势垒因受导体表面电场的影响而变形，位能势垒宽度渐渐变窄，气体分子中最外层电子可以有机会穿隧而出至导体样品表面时，气体分子即离化成“气体离子”。