Color transparency after the NE18 and E665 experiments Outllok and perspectives at CEBAF

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3 Colorimetry1205

What is Colorimetry?
• Colorimetry is using color intensity measurements to determine the amount of a substance dissolved in solution.
• Measure samples with a colorimeter or spectrophotometer
– Filtration – Dilution – Digestion – Distillation
Running the Test
• Pour sample into Nhomakorabea clean sample cell
– Rinse cell with sample before filling to volume
Running the Test
• Add reagents to the sample, as indicated in the procedure
Reagents
• Convenient reagent packaging
– Permachem foil pouches – AccuVac vials – Test ‘N Tube Plus – Test ‘N Tube
Read the Sample
• After the reaction period, wipe sample cell clean, place into instrument, and touch the Read key
How Does the Spectrophotometer Read a Sample?
• Zero the instrument

电子衍射

电子衍射电子衍射实验对确立电子的波粒二象性和建立量子力学起过重要作用。

历史上在认识电子的波粒二象性之前，已经确立了光的波粒二象性．德布罗意在光的波粒二象性和一些实验现象的启示下，于1924年提出实物粒子如电子、质子等也具有波性的假设。

当时人们已经掌握了Ｘ射线的晶体衍射知识，这为从实验上证实德布罗意假设提供了有利因素．1927年戴维孙和革末发表他们用低速电子轰击镍单晶产生电子衍射的实验结果。

两个月后，英国的汤姆逊和雷德发表了用高速电子穿透物质薄片的办法直接获得电子花纹的结果。

他们从实验测得电子波的波长与德布罗意波公式计算出的波长相吻合，证明了电子具有波动性，验证了德布罗意假设，成为第一批证实德布罗意假说的实验，所以这是近代物理学发展史上一个重要实验。

利用电子衍射可以研究测定各种物质的结构类型及基本参数．本实验用电子束照射金属银的薄膜，观察研究发生的电子衍射现象。

一实验目的1 拍摄电子衍射图样，计算电子波波长。

2 验证德布罗意公式。

二实验原理电子衍射是以电子束直接打在晶体上面而形成的。

在本仪器中我们在示波器的电子枪和荧光屏之间固定一块直径约为2.5cm 的圆形金属膜靶，电子束聚焦在靶面上，并成为定向电子束流。

电子束由13KV 以下的电压加速，通过偏转板时，被引向靶面上任意部位。

玻壳上有足够大的透明部分，可以观察内部结构，电子束采用静电聚焦及偏转。

若一电子束以速度ν通过极薄的晶体膜，这些电子束的德布罗意波的波长为：p h='λ （1）式中普朗克常数，p 为动量。

设电子初速度为零，在电位差为U 的电场中作加速运动。

在电位差不太大时，即非相对论情况下，电子速度c <<ν（光在真空中的速度），故02201/m c m m ≈-=ν，其中0m 为电子的静止质量。

它所达到的速度ν可由电场力所作的功来决定：m p m eU 22122==ν （2）将式（2）代入（1）中，得：U em h 12='λ （3）式中e 为电子的电荷，m 为电子质量，h 为普朗克常量，然后将0m 、h 、e 代入（3）得U 225.1='λ （4）其中加速电压U 的单位为V ，λ的单位为1010-米。

ASME试卷

ASME 规范产品Ⅲ级射线检验人员专业考试试题SPECIFIC EXAMINATION QUESTIONS FOR LEVEL ⅢPERSONNEL OF RADIOGRAPHIC TESTING FOR THE ASME CODE PRODUCTS姓名得分NAME_____________GRADE_____________In the following selecting questions,choose the letter represents the right answer into the brackets; in the judging questions, fill ○ or × to indicate whether correct or not.对下列选择题，选择代表正确答案的字母填入括号内；对判断题，在括号内填入○或×，以示其正确与否。

1.The function of soup is reducting the exposed AgBr grain into metal Ag.( )1.显影液的作用是把已曝光的AgBr颗粒还原成金属银。

（）2.New or stopping using or long time X-ray inxtrument should be “training”before operation ,its aim is improve vacuum of X-ray tube.( )2.新的或长期停用的X光机，使用前要进行“训练”，其目的是提高X光管的真空度。

（）3.In the course of exposure ,the lend intensifying screen closely contact with the X-ray film can improve the density of negative,its reason is ( ).A.the lead intensifying screen may emit fluorescence and visiblelight ,and accelerate sensitization of film.B.The lead screen may absorb scattering ray.C.Prevent back scattering causing fog on film.D.The lead screen can emit electron radiated by X-ray and γ-ray,therefore is helpful to exposure of film.3.曝光过程中，与X射线胶片紧密接触的铅增感屏可提高底片黑度，其原因是（）A、铅增感屏会发生荧光和可见光，从而加快胶片感光B、铅屏可吸收散射线C、防止背散射造成胶片灰雾D、铅屏受X和γ射线照相会发射电子，从而有助于胶片感光。

外文翻译光学

2011 届本科毕业设计(论文)外文文献翻译学院：专业：姓名：学号：外文出处：Thickness and refractive index(用外文写)Measurements using multiplebeam interference fringes附件： 1.外文资料翻译译文；2.外文原文。

使用多波束,干涉条纹测量厚度和折光率摘要我们报告中采用的光干涉仪利用在表面平等的彩色条纹确定了分离薄膜厚度和折射率在一个比较广的范围内。

特别是，在二边缘位置的未测量的基础上我们将展示如何计算两个表面分离距离（膜厚度）。

我们讨论了测量精度，尽管所有的距离理论精度是1Å，在实践中我们表明，在距离比较大的情况下很难达到这样的精度。

在表面力装置试验中，通常使用3或5层的干扰仪。

尽管虽然三层干涉仪分析适用于任何数量的层次，但是在这里我们使用3层干涉仪。

当透明的基质层（通常是云目表）接触时，pth-order 的边缘位置0p λ通常在可见光的波长范围内。

基板表面后，相隔的距离为d 的位置形成三层干涉。

边缘转移到更长的波长，他们的新位置D P λ根据所给公式2242sin()2tan()4(1)(1)cos()D P med D P D P Y D Y πμμλπμλπμμμλ=--+ （1），假设没有分散（我们在后面讨论这点），对上面的公式转化变成000102200112sin()12tan()1(1)cos()(1)1p D P p p med D P p D P p p D λλμπλλπμλλλμπμλλ----=-+±-- （1a ），其中Y 是每个基板光学厚度（我们将谈论光学与物理厚度之间的差别）μ =μ/ μ med,其中，μ（μγ或μβ）和μmed 分别是云母和中间介质的折射率，在式中。

（1a ），+和 - 分别指到p 奇数偶数阶边缘，也可用其他方法计算厚度（例如，参考[4]);然而简单的方程（1a ）使其成为最常用的方法。

北京理工大学数码相机性能评测实验二

数码相机性能评测实验二噪声及色彩还原性测试实验目的:1、了解数码相机光电转换函数（OECF测试标版，掌握其使用方法2、掌握数码相机噪声测试方法。

3、了解数码相机色彩还原性测试标板。

4、掌握数码相机色彩还原性测试方法实验要求：1、使用数码相机拍摄24色标准色卡。

2、使用Imatest软件的Colorcheck模块测量数码相机色彩还原性。

3、使用数码相机拍摄OECF测试标版。

4、使用Imatest软件的Stepchart模块测量数码相机噪声5、了解Imatest噪声和色彩还原性测试结果的含义。

1、使用数码相机拍摄24色标准色卡2、使用Imatest软件的Colorcheck模块测量数码相机色彩还原性相机型号：红米1S测试标版：反射色彩饱和度:121.1%色差C corr平均值6.12最大值16.5△C uncorr :平均值9.57最大值24△ E ：平均值11.8最大值23.6测试人员：李斌测试日期：2015年11月25日▲Figure 3: a*b* color error 一 _ 一・、File曰M 4爲2紳◎凰石甬整个坐标是较大的CIELAB色域，而较小的、被灰线画起来的范围则是相机本身的SRGB色域软件在色彩偏移对照方面的处理结果图□匡IIMG 201 51125 1B4616.jpgInner squares: CoiarCheDkEr ref AA nee: with.w/o HSL luminance oorr.15-D6G-2O15 21:2&:55 sRGB EKPO&LTA enoc 3-0.26 f-alops1.9 [0.052]0P 9 [D 131]180 (+4.6] -16 [+0 4]HTet)n versionWhite Bal Error:AC [HSV Saturation ® })Degrees K (Mireds]hase3 3[0 045]3.7fD.O 3S]3 占[0”04l]4.0 [0 001)<392 (+S.9 | ・30& (+7.7] -280 (+7.1 | A85(+18.1]Exaggerated White Balance error比较上图中的各方格的区域 Zonel和Zone2,发现亮度接近，说明该相机的曝光误差小。

卫星海洋学

海洋遥感技术1、选择填空（20分）2、名词解释（8个*2=16分）3、简答题（5道，40分）4、计算题、综合题。

计算题好像说是一道题，分值老师讲的不是很清楚，我也听不清楚。

一、填空题1、传感器的扫描方式：交叉轨道扫描，推扫式扫描，混合式扫描，圆锥式扫描等。

2、（第四章）1997年美国发射的装载着宽视场海洋观测传感器SeaWiFS的SeaStar 卫星，SeaStar卫星的循环周期（recurrent period）是③，传感器SeaWiFS完成全球覆盖的重复周期为②，每个重复周期（repeat period）包含29个轨道周期，每个轨道周期（orbit period）为1.648小时。

在低纬度地区，SeaWiFS 的再访问时间（revisit period）是②；在高纬度地区，SeaWiFS的再访问时间（revisit period）是①。

（选择：①1天；②2天；③16天；④35天）3、（第八章）MODIS热红外通道辐亮度L i通过__③___ 与该通道的黑体温度T i相联系；MODIS热红外通道的黑体温度T i通过__④___ 与海表面温度相联系。

（选择：①基尔霍夫定律，②经验公式，③普朗克定律，④瑞利-金斯定律）4、（第九章）平静海面的微波亮温T通过_④+⑤__ 与海面发射率e相联系，海面发射率e通过__①__ 与菲涅耳反射率ρ相联系，菲涅耳反射率ρ通过__②__ 与相对电容率εr相联系，相对电容率εr 通过__③__ 与海表面温度和盐度相联系。

（选择：①基尔霍夫定律，②菲涅耳公式，③德拜方程，④瑞利-金斯定律，⑤发射率定义）5、（第九章）天线的半功率波束宽度与_②_成正比，与_①_成反比。

（选择：①天线的孔径D，②电磁波的波长λ，③观测的天顶角）6、（第九章）微波辐射计SSM/I反演风速的两种算法（包括SSM/I-GSW算法和SSM/I-GSWP算法）在风速小于15m/s条件下反演精度达到_①_。

费城超时空实验是真的吗

费城超时空实验是真的吗费城实验，又叫费城时空实验，“彩虹计划”大家都应该听过，那么费城超时空实验是真的吗？这也许只有当事人才知道了。

费城实验（英文：Philadelphia Experiment）是一项流传已久的传闻，宣称美国海军在1943年10月28日曾在宾夕法尼亚州费城一船坞举行秘密实验，使一艘护卫驱逐舰埃尔德里奇号（USS Eldridge DE-173）在观察者眼中隐形。

该实验也叫费城计划，又称彩虹计划。

所有参与计划的船员都否认曾有任何事件发生，除了一位目击者宣称目击了整个实验发生的经过。

由于没有任何直接证据，且实验内容缺乏严谨的科学理论基础，费城实验传闻的真实性因而普遍受到质疑，并被认为是单纯的都市传奇。

本文选自《飞碟探索》杂志费城超时空实验简介：“1943年10月，美国海军在费城进行了一次人工磁场的机密试验，即著名的‘费城实验（The Philadelphia Experiment）’，实验成功地将一艘驱逐舰及全体船员投入另一空间。

在实验过程中，实验人员启动脉冲和非脉冲器，使船只周围形成了一个巨大的磁场。

随后整条船被一团绿光笼罩着，船只和船员也开始从人们的视线中消失。

实验终止时，舰船已被移送到了479公里以外的诺福克(Norfolk)码头。

此后，一些船员身上仍留有实验的反应，不论在家里，在街上，在酒吧间或饭店里，都会突然地消失又重现，让旁观者惊讶不已。

参与实验的主要负责人过几天后自杀身亡，临死前说过，这项实验与爱因斯坦的相对论有关。

这使得这项实验多添了一份神秘色彩。

费城实验：验证外星人行走通道实验的理论基础费城实验源于“彩虹”计划，是一次军舰隐形实验。

其最初的目的是让舰艇借助强烈的电磁场来干扰和躲避敌方龟雷的攻击，后来延伸为在周围空气中产生强磁场，使敌人的雷达探测不到自己的存在。

美军考虑对该实验的绝密性，将“彩虹”计划的实验对象定为“艾尔德里奇”号驱逐舰。

1943年6月，“艾尔德里奇”号被安装上了数吨电子实验设备。

电磁诱导透明

电磁诱导透明某种介质强烈地吸收某一频率的光束,而当再加一束能被介质吸收的光束时,介质对第一束光就不再吸收了.这种现象称为电磁诱导透明,简称EIT(electromagnetic induced transparency).如图1所示,介质中的原子构成三能级系统,其中量子态|1〉和|2〉代表原子的2个基态,而量子态|0〉代表公共的激发态,这种能级系统属于∧类型.引起态|2〉和|0〉之间跃迁的激光称为探测激光,而引起态|1〉和|0〉之间跃迁的激光称为泵浦激光.改变探测激光的频率,在不加泵浦激光时,得到如图2(a)所示的单一吸收峰,峰值对应的频率为共振频率ωs;加上泵浦激光时,如图2(b)所示,在一个较狭小区间,吸收被遏止了,相对来说,介质变得透明了.该过程揭示了在激光作用下原子内部的量子相干现象.下面用经典实验来演示电磁诱导透明现象RLC电路来模拟电磁诱导透明现象进行了实验验证。

如图3所示的RLC电路,此时由电感L1和电容C1及C构成的回路模拟泵浦振荡电路,该振荡电路的损耗取决于电阻R2的阻值.利用电感L2、电容C2和C构成的共振电路模拟原子,此时电阻R2表示激发态自发辐射衰减,电容C为2个电路所共有,模拟原子和泵浦场之间的耦合,决定了与泵浦跃迁相关的拉比频率,这里探测场用频率可调电压源Vs来模拟.该电路各元件参量如下:R1=0;R2=51.7Ω;L1=1 000μH;L2=1 000μH;C1=0.1μF;C2=0.1μF.用于模拟原子的回路只有1个共振频率,表示原子激发态能量.也就是说,当达到共振时这个电路被激发的概率将会达到最大.由于在这种情况下有2种方法来实现激发,故涉及的问题实际是对三能级∧结构原子的模拟,即对应“原子”的振荡可以直接由所加电压Vs 来激发,也可通过其与泵浦回路的耦合来激发.这里研究诱导透明是通过分析从电压源Vs 传递到共振回路R2L2Ce2的功率与频率的依赖关系而得到,而实验用回路中电流对频率的依赖关系近似表示功率对频率的依赖关系.其中222C C CC C e += （1）为了定量描写这一系统,需要写出RLC 电路的回路方程.设L1=L2=L,回路电流为i1(t)= q1(t),i2(t)=q2(t),得到。

光电子能谱和反光电子能谱测导带和价带文献

Graphene/Substrate Charge Transfer Characterized by Inverse Photoelectron SpectroscopyLingmei Kong,†Cameron Bjelkevig,‡,§Sneha Gaddam,‡Mi Zhou,‡Young Hee Lee,|Gang Hee Han,|Hae Kyung Jeong,⊥Ning Wu,†Zhengzheng Zhang,†Jie Xiao,†P.A.Dowben,†and Jeffry A.Kelber*,‡Department of Physics and Astronomy,Nebraska Center for Nanostructures and Materials,Theodore Jorgensen Hall,855North 16th Street,Uni V ersity of Nebraska s Lincoln,Lincoln,Nebraska 68588-0111,United States,Department of Chemistry and Center for Electronic Materials Processing and Integration.Uni V ersity of North Texas,1155Union Circle #305070,Denton,Texas 76203-5017,United States,Department of Physics,Department of Energy Science,and Center for Nanotubes and Nanostructured Composites,Sungkyunkwan Ad V anced Institute of Nanotechnology,Sungkyunkwan Uni V ersity,Suwon,440-746Korea (ROK),and Department of Physics,Daegu Uni V ersity,Gyeongsan,712-714Korea (ROK)Recei V ed:September 9,2010;Re V ised Manuscript Recei V ed:October 26,2010Wave vector-resolved inverse photoelectron spectroscopy (IPES)measurements demonstrate that there is a large variation of interfacial charge transfer for graphene grown by chemical vapor deposition (CVD)on a range of dielectric or metallic substrates.Monolayer graphene grown by CVD on monolayer BN(0001)/Ru(0001)exhibits strong charge transfer from the substrate to graphene of 0.07(1)e -per carbon atom,as manifested by ﬁlling of the π*band and displacement of the Fermi level.IPES measurements of CVD single layer graphene on Ru indicate a substrate-to-graphene charge transfer from the substrate of 0.06(1)e -per carbon atom,in agreement with reported angle-resolved photoemission results.The IPES spectra of CVD single layer graphene on Ni(poly)and on Cu(poly)indicate 0.03(1)e -per carbon atom charge transfer from Ni and Cu substrates.Single layer graphene has also been grown by free radical-assisted CVD on MgO(111),resulting in a layer of graphene and an oxidized carbon interfacial layer between the graphene and the substrate.IPES measurements indicate that 0.02(1)e -per carbon atom charge is transferred from graphene to the MgO substrate.Additionally,IPES and photoemission data indicate that single layer graphene/MgO(111)exhibits a band gap.These data demonstrate that IPES is an effective method for precise measurement of substrate/graphene charge transfer and related electronic interactions,in part because of the extreme surface sensitivity of the technique,and suggest new strategies for extrinsic doping of graphene for controlled mobilities for device applications.1.IntroductionGraphene,due to extremely high room temperature electron/hole mobilities 1-3and polarizabilities,4,5is of great interest for nanoelectronic and spintronic device applications.Interfacial interactions of graphene with adjacent layers are therefore of practical importance,as both adsorbate-induced charge transfer and interaction with dielectric substrates can result in signiﬁ-cantly enhanced or reduced mobilities.Of interest for device applications,adsorbate-induced hole or charge transfer generally results in reduced mobilities but has resulted in enhanced Hall mobility,6while proximity to high-k dielectric substrates sometimes yields increased electron or hole mobility at room temperature,apparently through screening of carriers from charged impurities.7Graphene/substrate interactions may also yield a band gap in the graphene band structure,8and this is of critical concern in the development of graphene-based logic devices with true “off”states.Recently,wave (k )-vector resolved inverse photoelectron spectroscopy (IPES)has demonstrated the presence of substan-tial BN-to-graphene charge transfer 9for graphene grown byCVD on BN(0001)/Ru(0001).An order-of-magnitude enhance-ment of graphene room temperature mobility relative to graphene/SiO 2has recently been reported 10for graphene sheets physically transferred to BN substrates,consistent with predicted results for extrinsic doping,6but also possibly due to decreased phonon interactions with hexagonal BN(0001)layers.These facts,combined with monolayer sensitivity,11demonstrate the potential for IPES to delineate electronic interactions between graphene and substrates in a layer-by-layer fashion and to provide a quantitative basis for predicting the effects of such materials interactions on graphene electronic properties.We report here the results of IPES measurements of electronic charge transfer between graphene and various substrates,including BN/Ru(0001),Ru(0001),Ni(poly),Cu(poly),and MgO(111),as well as previously reported 12IPES data of graphene on SiC(0001).Notably,the IPES and photoemission data indicate the presence of a band gap for graphene/MgO(111),suggesting that graphene on this substrate may be of particular utility for logic device applications,with the band gap allowing a true “off”state.IPES data further indicate that signiﬁcant interfacial charge transfer and band-ﬁlling do not appreciably alter the fundamental conduction band electronic structure of graphene and suggest practical routes toward the formation of extrinsically doped graphene layers with controlled electron mobilities for device applications.*To whom correspondence should be addressed.E-mail:Kelber@.†University of Nebraska s Lincoln.‡University of North Texas.§Present address:Intel Corp.,4100Sara Rd.SE,Rio Rancho,NM 87124.|Sungkyunkwan University.⊥Daegu University.J.Phys.Chem.C 2010,114,21618–216242161810.1021/jp108616h 2010American Chemical SocietyPublished on Web 11/17/20102.Experimental MethodsThe fabrication of the monolayer graphene/BN/Ru(0001)sample,and characterization by scanning tunneling microscopy/spectroscopy (STM/STS),low energy electron diffraction (LEED),Raman spectroscopy,photoemission spectroscopy (PES),and IPES measurements,has been previously reported.9The data are included here for direct comparison with results for graphene on other substrates.Graphene on Ru(0001)was prepared in a manner similar to that described in the literature 13by CVD of C 2H 4at 1×10-8Torr,2min of exposure at 700K on Ru(0001),followed by annealing in ultrahigh vacuum (UHV)to 1000K,in a UHV system described previously.14Graphene layers on polycrystalline substrates s Ni(poly)and Cu(poly)s were prepared by CVD and characterized as described previously.15,16A graphene ﬁlm was also grown by CVD using thermally dissociated C 2H 4(free radical assisted CVD;FRA-CVD)on a MgO(111)single crystal substrate in a system equipped for LEED and X-ray excited photoelectron spectroscopy (XPS),which has been described previously.17,18A more detailed account of the preparation and characterization of graphene ﬁlms on this surface,and the associated interfacial chemistry,will be published elsewhere.Brieﬂy,a MgO(111)substrate 1cm in diameter and 0.5mm thick was cleaned at room temperature by exposure to atomic oxygen from a commercially available thermal catalytic cracker (Oxford Applied Instruments).A ﬂux of dissociated C 2H 4was supplied from the same source,which has also been described previously.19,20XPS spectra were acquired at a constant pass energy (44eV)using Mg K R radiation and analyzed using commercial software (ESCA-TOOLS)according to standard methods.IPES data were acquired as described previously,21,22in the isochromat mode using a Geiger -Mu ¨ller detector set to detectphotons at 9.7eV.The IPES measurements were limited by aninstrumental resolution of ∼400meV.The IPES spectra were acquired along the surface normal.Thus,the relative positions of the π*and σ*bands in the IPES data reported here are at the Γpoint of the Brilloin zone,at the σ*minimum.9,12The angle-integrated PES and wave vector-resolved IPES were undertaken to study the molecular orbital placement of both occupied and unoccupied orbitals of graphene on MgO but here have not been corrected for ﬁnal state effects arising from the insulating nature of the substrate,which may lead to an overestimation of the true band gap.In addition to such effects,the angle-integrated nature of the PES measurements and wave vector-resolved nature of the IPES measurements obviate the use of these data to determine energy splitting between speciﬁc valence and conduction band features,such as the π-π*splitting.PES data were acquired using a He I source UV source (21.2eV)in the same vacuum system and with the analyzer aligned with the surface normal.3.Results3.1.Characterization of Single Layer Graphene on Ru(0001).A cleaned and ordered Ru(0001)single crystal was exposed to 1.2L of C 2H 4at 700K,followed by annealing to 1000K in UHV.A sharp,bifurcated LEED pattern was observed (Figure 1a),due to the Ru and graphene lattice mismatch.Assuming a Ru lattice constant of 2.7Å,the outer diffraction spots (Figure 1b)indicate a lattice constant of 2.5(1)Ås graphene.The thickness of the graphene overlayer was estimated from decreases in intensity of a Ru Auger feature (Figure 1c,arrow),which does not overlap with the C(KVV)Auger ing a calculated 23inelastic mean free path of 10.5Å,a total average thickness of the graphene layer afterFigure 1.Characterization of single layer graphene on Ru(0001).(a)LEED (beam energy )70eV)after 1.2L C 2H 4exposure to Ru(0001)at 700K,followed by annealing to 1000K in UHV.(b)Line scan of LEED pattern,showing bifurcated spots.(c)Auger spectra before/after ethylene exposure and annealing.Changes in peak-to-peak height for marked Auger feature (arrow)were used to calculate changes in intensity and therefore average thickness of carbon overlayer.Graphene/Substrate Charge Transfer Characterized by IPES J.Phys.Chem.C,Vol.114,No.49,201021619annealing is estimated at 1.3((0.2)monolayers.The uncertainty in this ﬁgure derives from the fact that the experimental error in the reproducibility of absolute Auger electron intensities in this system,conservatively estimated at 10%.Exposure of this sample to ambient resulted in no discernible evidence of oxidation as determined by Auger or changes to the LEED pattern.3.2.Characterization of Single Layer Graphene on MgO(111).A graphene ﬁlm was grown on an MgO(111)single crystal by ﬁrst cleaning the surface in atomic O at room temperature and then exposure of the (disordered)MgO surface to a ﬂux of dissociated C 2H 4at ∼600K (5×10-7Torr,25min).No LEED pattern was observed before or after the exposure to dissociated ethylene.From the C(1s)XPS spectrum (Figure 2a),a total average carbon thickness of 3Åwas determined.The sample was re-exposed to ambient and placed on a different sample holder to permit more efﬁcient heating.Subsequent annealing to 1000K in UHV produced the observed change in C(1s)XPS (Figure 2a).(Because of the signiﬁcant and variable sample charging,the peak maxima of the two carbon spectra have been aligned to compare changes in peak shape.)The total average thickness of the carbon layer after annealing to 1000K was 2.5Å,indicating that exposure to ambient and subsequent annealing in UHV had resulted in no signiﬁcant increase in surface carbon.The annealing process did,however,result in a signiﬁcant broadening of the C(1s)spectrum (Figure 2a)toward higher binding energy,indicating the presence of surface carbon in multiple oxidation states.After annealing,the expected 6-fold LEED image for a graphene ﬁlm was observed (Figure 2b).Because atomically clean MgO(111)(1×1)yields a 3-fold LEED pattern at this beam energy (∼75eV),24the presence of a 6-fold LEED pattern indicates formation of a graphene surface layer.This conclusion is corroborated by the fact that decomposition of the XPS spectrum of the annealed sample into two regions s one centered near 292eV binding energy (uncorrected for charging)with the same fwhm as the spectrum prior to annealing and the second including the higher binding energy tail s indicates that the thickness of the lower binding energy component is 1.5Å,corresponding to a monolayer of graphene.The XPS data in Figure 2,however,indicate that carbon is present on the MgO surface in multiple oxidation states.Subsequent exposure of the annealed sample to ambient resulted in no signiﬁcant changes to the LEED pattern (Figure 2b).The LEED and XPS data together therefore indicate the formation of an ordered graphene layer in thepresence of an interfacial layer that includes carbon in higher oxidation states.3.3.Inverse Photoemission Measurements of Interfacial Charge Transfer.The position of a speciﬁc conduction band feature in the IPES spectrum,relative to the Fermi level,provides quantitative information on charge transfer between substrate and graphene layers.The IPES data are displayed in Figure 3for single layer graphene on BN(0001)/Ru(0001)(Figure 3a),on Ru(0001)(Figure 3b),on Cu(poly)(Figure 3c),on Ni(poly)(Figure 3d),and compared to the previously reported 12data for multilayer graphene grown on SiC(0001)by thermal evaporation (Figure 3e)and to our results for graphene/MgO(111)(Figure 3f).Although charge transfer between the single layer graphene and the SiC substrate is known to dependFigure 2.Graphene formation on MgO(111)(a)C(1s)XPS spectra after exposure of a clean,disordered MgO surface to dissociated ethylene at 5×10-7Torr,25min at ∼600K (open circles),and after subsequent exposure to ambient and annealing in UHV to 1000K (solid line).The two spectra have been manually aligned and have not been corrected for sample charging.(b)Corresponding LEED pattern at 75eV beam energy after annealing to 1000K.Figure 3.IPES spectra of graphene on various substrates as labeled (background subtracted):(a)BN(0001)/Ru(0001),(b)Ru(0001),(c)Cu foil,(d)Ni foil,(e)SiC (adapted from ref 12),and (f)MgO(111).Features are labeled as (1)scattering from the π*,(2)σ*and low lying π*,and (3)σ*(Γ1+).21620J.Phys.Chem.C,Vol.114,No.49,2010Kong etal.on the Si(n type)vs C(p type)nature of the substrate surface termination,25,26such interface effects(including band gap formation)are rapidly screened upon multilayer graphene formation.8Because the data of Forbeaux et al.(Figure3e)were acquired for multilayer graphene,12we take the corresponding IPES spectrum as a standard for a graphene layer with a weakly interacting substrate,with negligible interfacial charge transfer. The spectra in Figure3are plotted as a function of energy from the Fermi level,E-E F.The data show the main features in the vicinity of the Fermi level and are plotted relative to the features identiﬁed for multilayer graphene on SiC,12seen also with single crystal graphite.27Because of imperfections in some of the graphene overlayers,the spectral features are similar but not identical due to scattering contributions.In addition,the features observed in IPES shift progressively closer to the Fermi level as the substrate is varied from MgO(Figure3f)to SiC (Figure3e),to Ni(Figure3d)or Cu(Figure3c),to Ru(Figure 3b),and then to BN/Ru(Figure3a).This is evidence of band-ﬁlling.28,29The IPES spectrum displays only the unoc-cupied density of states,but because the IPES spectra are extremely surface sensitive,the degree of charge transfer between the substrate to or from graphene can be quantitatively estimated from the binding energy positions of known features (e.g.,the mainσ*feature)in the spectrum relative to the Fermi level.At a charge neutral condition,the Fermi energy of free-standing graphene coincides with the conical point(the Dirac point),and the density of states is dominated near the Fermi level by the Dirac cone.26The introduction of extra electrons to grapheneﬁlls any empty states near the Fermi level E F,with states closest to the Fermi levelﬁlledﬁrst,thus decreasing the energy difference of conduction band features relative to E F.In contrast,the subtraction of electrons from graphene increases this energy difference.It can be seen in Figure3that corre-sponding features in the IPES spectra of graphene on Ni,Cu, Ru,and BN shift progressively closer to the Fermi level, indicating increasing charge transfer from the substrates to graphene.The bands of graphene on MgO,however,shift away from the Fermi level and indicate charge transfer from graphene to the MgO substrate.The amount of charge transfer can be calculated from the shift of the Fermi level relative to the conduction band edge.A larger shift indicates more charge transfer.The amount of charge transferred is proportional to the shift of the Fermi level for small amounts of charge transfer, because of the density of states being dominated by the unique band structure near the Fermi level.The amount of charge transfer roughly equals the shift of the Fermi level×0.02e-/ carbon atom.1For larger shifts,a density of states correction is required.Quantitative measurements of interfacial charge transfer derived from the IPES spectra(Figure3)are listed in Table1.Results of the analyses of the IPES spectra in Figure3are in agreement with results obtained by other experimental methods or by theory.The IPES-deduced charge transfer from BN(0001)/ Ru(0001)to graphene(Figure1a)indicates a substrate-to-graphene charge transfer of-0.07(1)e-/carbon atom(the negative sign indicating substrate-to-graphene charge transfer and the number in parentheses indicating the uncertainty in the last digit),in qualitative agreement with DFT calculations and consistent with a pronounced red shift of the2D Raman feature for this system(Table1).9This value is less than the previously reported value9due to the assumption(Figure3and Table1) of a charge neutral condition for multilayer graphene on SiC, not assumed previously.The interlayer charge transfer results obtained from analysis of the IPES spectra of single layer graphene/Ru(0001)(Figure1b),-0.06(1)e-/carbon atom,are in good agreement with the result of-0.05e-/carbon atom obtained by angle-resolved PES.13,30The large charge transfers determined for graphene/BN/Ru(0001)and for graphene/ Ru(0001)would indicate complete or partialﬁlling of the grapheneπ*band,eliminating or obscuring these features in the IPES spectrum.Consistent with this,theπ*feature is not observed for graphene/BN/Ru(Figure3a)9and is at least signiﬁcantly obscured for single layer graphene/Ru(0001) (Figure3b).The result of-0.03(1)e-/carbon atom for graphene on Ni(poly)(Figure1c)is in agreement with photoemission studies indicating weak substrate-to-graphene charge transfer due to Ni(3d)/graphene(π)mixing31and in good agreement with DFT results32indicating a0.35eV downward shift of graphene band features for this reason.A similar substrate-to-graphene charge transfer is observed for graphene/Cu(poly)(Figure1d). Using the multilayer graphene/SiC IPES spectrum(Figure3e) as the“standard”for zero interfacial charge transfer,a slight [+0.02(1)]e-/carbon atom charge transfer is observed from graphene to the MgO(111)substrate(Figure3f).These latter measurements cannot be taken as accurate as theﬁnal state effects have not been completely excluded and cannot be taken fully into account from this data.Suchﬁnal state effects will result in the occupied states and unoccupied states appearing to be placed farther from the Fermi level than may be in fact true in the charge neutral ground state.33The effects of the MgO substrate on the electronic structure of graphene deposited by FRA-CVD can be determined in further detail by combining angle integrated PES and wave vector-resolved IPES spectra(Figure4).The data are plotted relative to a common Fermi level(E F).The assignment of theTABLE1:Comparison of2D Peak Positions and Substrate/Graphene Charge Transfersample a G peak position(cm-1)2D peak position(cm-1)IPES-determined chargetransfer(e-per carbon atom)b remarks/charge transferSLG/BN(0001)/Ru(0001)1540924009-0.07(1)previously reported value,-0.129 SLG/Ru(0001)no spectrum43no spectrum43-0.06(1)ARXPS value,-0.0513,30DLG/Ru(0001)159943267843042SLG/Cu(poly)159044267844-0.03(1)SLG/Ni(poly)158045,46270945,46-0.03(1)-0.02SLG/SiC1591.547271047-0.0227MLG/SiC15904827204808SLG/MgO+0.02(1)a SLG,single layer graphene;DLG,double layer graphene;and MLG,multilayer graphene.b A negative charge transfer number refers to charge donation from the substrate to graphene(n type doping);a positive charge transfer number refers to charge transfer from graphene to the substrate(p type).The amount of charge transfer equals the shift of the Fermi level×0.02e-/carbon atom.The number in parentheses is the uncertainty in theﬁnal digit.Graphene/Substrate Charge Transfer Characterized by IPES J.Phys.Chem.C,Vol.114,No.49,201021621valence band features in the PES spectrum is in good agreement with results on,for example,Ni(111),34while the conduction band features are in accord with assignments for graphene/SiC(0001).12The inversion of relative π/σand π*/σ*ordering (Figure 4)reﬂects the angle-integrated nature of the PES spectrum as opposed to the k -resolved nature of the IPES measurements.Signiﬁcant sample charging was encountered for graphene/MgO(111),and in this case,the placement of the Fermi level is approximated from the position of a copper contact to the sample.The resulting placement of the Fermi level near the top of the valence band edge (Figure 4),however,is consistent with observed (Figure 3f)slightly p type doping of graphene by MgO.A band gap is observed for graphene/MgO(111)(Figure 4).The magnitude of the band gap,∼1eV,is independent of the precise placement of the Fermi level.The presence of a substantial band gap is consistent with charging encountered for the monolayer sensitive-IPES and LEED measurements.A previous brief report 35also suggested the formation of an insulating or semiconducting graphene ﬁlm resulting from carbon evaporation onto MgO(111).4.DiscussionThe above data demonstrate the utility of IPES for assessing interfacial charge transfer between graphene and dielectric or metallic substrates.These data also suggest new device ap-plications for certain graphene/dielectric heterostructures.The results for graphene/BN/Ru indicate substantial charge transfer to graphene,essentially ﬁlling the π*band.9Adsorbate-induced charge transfer has been correlated 6with order-of-magnitude increases in electron mobility.Recent transport measurements on graphene sheets physically transferred to BN substrates 10indicate just such a factor of 10increase in room temperature mobility relative to graphene/SiO 2.Other factors,such as substrate phonon effects,may have impacted the above result.However,the correlation between observed charge transfer in graphene/BN heterojunctions 9and predicted 6and observed 10effects upon electron transport are certainly motivation for further study of such systems for device applications.This is the ﬁrst report of the structural (LEED),chemical (XPS),and electronic (PES,IPES)characterization of graphene layer formation on MgO(111).The results,showing the presence of a band gap,are consistent with a brief abstract published previously for graphene deposition by MBE on this surface 35but indicate that the formation of a graphene layer (Figure 2)is associated with the formation of an oxidized carbon interfaciallayer.Indeed,the higher binding energy tail of the XPS C(1s)spectrum obtained after annealing to 1000K (Figure 2a)is similar to the XPS C(1s)spectrum for graphene oxide.36Band gaps varying from ∼0.237to 1.7eV 38for oxidized graphene ﬂakes have been reported.However,the XPS data (Figure 2a)indicate two layers of carbon,while the surface sensitive LEED (Figure 2b)and PES/IPES measurements (Figure 4)indicate a graphenelike surface layer,with intact πand π*features.One possibility is that the sample consists of an oxidized carbon interfacial layer,hexagonally ordered,interacting with a graphene overlayer.The similar hexagonal symmetry of both layers would lead to A -B symmetry breaking in the graphene layer,and similar arguments have been advanced for formation of a 0.26eV band gap for single layer graphene on SiC(0001).3The evolution of the oxidized carbon region upon annealing (Figure 2a)further suggests that this oxidized carbon interfacial layer reﬂects a fundamental aspect of carbon/MgO(111)surface chemistry at elevated temperatures.The possible formation of BN(0001)and then graphene/BN heterojunctions on MgO(111)are suggested by these data,as a route toward the formation of extrinsically doped graphene layers on a high-k dielectric ﬁlms and for moderating the effects of carbon/MgO interfacial interactions for device applications.The fact that MgO(111)can be grown on Si(100)39is further motivation for examining this system from the point of view of future device applications.Finally,the recent report of graphitic nanoﬂake formation on MgO powders under CVD conditions 40suggests that graphene growth on other MgO orientations or on amorphous substrates might be possible.The effects of charge transfer on the change of the energies of graphene Raman spectral features 41-48is of practical interest in monitoring doping interactions involving graphene layers.The reported energy of Raman “G”(ring breathing mode)and “2D”(a two phonon mode)features for graphene on various substrates are therefore compared in Table 1.As shown in Table 1,the 2D position for graphene/BN(0001)/Ru is red-shifted by ∼300cm -1from the 2D energy for graphene on other substrates,and this also corresponds to a large charge transfer to graphene of 0.07(1)e -/carbon atom.The energy of the corresponding G feature s 1540cm -1s is only slightly red-shifted relative to the other G mode energies (Table 1)or to the corresponding energy in HOPG.9The other graphene Raman spectra exhibit 2D features in the region of 2670-2710cm -1,and G feature energies in the range of 1580-1600cm -1,corresponding to negligible interlayer charge transfer ((0.02e -/carbon atom).Importantly,although the monolayer graphene/Ru(0001)system exhibits signiﬁcant substrate-to-graphene charge transfer [-0.0.6(1)e -/carbon atom;Figure 3],no Raman spectrum is observed for single layer graphene on Ru(0001).43This is consistent with a large charge transfer,as the strong interactions required for large charge transfers on metal substrates can also lead to overdamping of the vibrational mode intensities of graphene in the Raman spectra.The data in Table 1therefore indicate that the energies of graphene Raman features for graphene on different substrates are at best very qualitative guides to interlayer charge transfer.Our own measure of the Raman shifts,however,indicates that there is a likely mode stiffening of the G band with charge abstraction from the graphene layer,even if slight,as indicated in Figure 5.This is in consistent with the previous report for phonon stiffening in carbon nanotubes.49As a ﬁnal point,it is worth noting key differences between IPES and near-edge X-ray absorption ﬁne structure spectroscopy (NEXAFS),which is also an important probe of conduction bandFigure bined PES and IPES of graphene on MgO substrates (background subtracted).For assignment of the features in the valence and conduction bands,see refs 34and 12,respectively.21622J.Phys.Chem.C,Vol.114,No.49,2010Kong etal.structure.The IPES data (Figures 3and 4)exhibit a π*-σ*splitting of ∼2eV,in agreement with previously reported data for graphene/SiC(0001).12In contrast,the corresponding splitting in NEXAFS for graphene is ∼8eV,50with a similar value for graphene oxide.51While some effects are undoubtedly due to initial state/ﬁnal state matrix element effects [the initial state in NEXAFS is the C(1s)level)]as well as NEXAFS ﬁnal state excitonic interactions (hole in 1s,electron in π*or σ*),the principle difference is due to the fact that NEXAFS is an angle-integrated measurement and samples the whole of the Brillouin zone,whereas the corresponding IPES value will vary signiﬁ-cantly with the speciﬁc geometry of the measurement because of the speciﬁc wave vector sampling.125.ConclusionIn summary,the data presented here demonstrate that IPES is a quantitative guide to the transfer of charge between graphene and metallic or dielectric substrates.The IPES data show signiﬁcant charge transfer of -0.07(1)e -/carbon atom from BN(0001)/Ru(0001)9and -0.06(1)e -/carbon atom for single layer graphene/Ru(0001),more than the IPES-determined charge transfer from monolayer Cu or Ni to graphene (Figure 3and Table 1)and in excellent agreement with reported results for graphene/Ru(0001)based on angle-resolved photoemission.13,30PES/IPES data demonstrate that a ∼1eV band gap occurs for graphene on MgO(111).Furthermore,IPES data for graphene on a variety of substrates indicate that interlayer charge transfer can occur by band ﬁlling without signiﬁcant distortion of the graphene electronic structure.This suggests that IPES can serve as a guide to potential graphene doping strategies based on measurements of charge transfer and effective masses calculated from dispersion measurements.Acknowledgment.Work at UNT was supported by the Global Research Consortium of the Semiconductor Research Consortium under Task ID 1770.001.Y.H.L.is supported by the Star-faculty program and WCU (World Class University)program through the KRF funded by the MEST (R31-2008-000-10029-0),and H.K.J.is supported by the Basic Science Program through the National Research Foundation of Korea funded by the MEST (2010-0004592).References and Notes(1)Novoselov,K.S.;Geim, A.K.;Morozov,S.V.;Jian, D.;Katsnelson,M.I.;Grigorieva,I.V.;Dubonos,V.;Firsov,A.A.Nature 2005,438,197.(2)Berger,C.;Song,Z.;Li,T.;Li,Z.;Ogbazghi,A.Y.;Feng,R.;Dai,Z.;Marchenkov,A.N.;Conrad,E.H.;First,P.N.;de Heer,W.A.J.Phys.Chem.B 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科技英语翻译赵玉闪3567章习题与答案

科技英语翻译赵玉闪3567章习题与答案1.The thickness of a tooth measured along the pitch circle is one half the circular pitch.沿节圆所测得的齿厚是周节的一半。

2.The earthquake measured 6.5 on the Richter scale.这次地震的震级为6.5力士震级。

3.We must reflect what measures to take in case of any accidental collapse of a bed .我们必须考虑一下如果层床意外崩塌应该采取什么措施。

4.In the transistor the output current depends upon the input current ,hence it is acurrent-operated device.在晶体管中，输出电流取决于输入电流，因此，晶体管是电流控制器件。

5.The relay is operated by a current of several milliamperes.继电器由数毫安电流起动。

6.The hearing aids are operated from batteries.助听器用电池供电7.Either of two reactions may be in effect in the reduction of iron oxide with carbon.在用碳还原氧化铁时，两种反应中的每一种都可能发生8.Alloys belong to a half-way house between mixtures and compounds.合金是介于混合物和化合物的中间结构9.The spindle rotates simultaneously round two axes at right angles to each other.钉子同时绕两个相互垂直的轴旋转10.An electron is an extremely small corpuscle with negative charge which rounds about thenucleus of an atom.电子是绕原子核转动且带有负电荷的微粒11.The rudder serves the purpose of yawing the airplane to the right or left.方向舵的用途是使飞机能够左右偏航12.Each of these compounds boils at a different temperature.这几种化合物的沸点各不相同13.After more experiments ,Galileo succeeded in making a much better telescope.经过一些实验后，伽利略成功的造出了一架好的多的望远镜14.During the weo and half hour talk, the two sides exchanged views on the choice of terms ofpayment, but they made no mention of the mode of transportation.在两个半小时的商谈中，双方就付款方式交换了意见，但却没有提到运输方式15.The application of electronic computers makes for a tremendous rise in labor productivity.使用电子计算机可以大大提高劳动生产率16.The maiden voyage of the newly-built steamship was a success.那艘新建轮船的首航是成功的17.About 20 kilometers thick , this giant umbrella is made up of a layer of ozone gas .地球的这一巨型保护伞由一层臭氧组成，其厚度约为20公里。

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arXiv:nucl-th/9406005v1 6 Jun 1994KFA-IKP(Th)-1994-201June1994

ColortransparencyaftertheNE18andE665experiments:OutllokandperspectivesatCEBAF.∗

J.Nemchik1,3),N.N.Nikolaev2,3andB.G.Zakharov21)InstituteofExperimentalPhysics,SlovakAcademyofSciences,

Watsonova47,04353Kosice,SlovakRepublik2)L.D.LandauInstituteforTheoreticalPhysics,GSP-1,117940,

ul.Kosygina2,V-334,Moscow,Russia3)IKP(Theorie),KFAJ¨ulich,D-52425J¨ulich,Germany

ABSTRACTCEBAFisahigh-luminocityfactoryofvirtualphotonswithvariablevirtualityQ2andtransversesize.ThismakesCEBAF,inparticularaftertheenergyupgradeto(8-12)GeV,anidealfacilityforuncoveringnewphenomena,andopeningnewwindows,attheinterfaceoftheperturbativeandnonperturbativeQCD.Wediscusscolortransparencyasthecaseforabroadprogramonelectroproductionofvectormesonsρ0,ω0,φ0andtheirradialexcitationsρ′,ω′,φ′atCEBAF.Wealsocommentonthesecondgenerationofexperimentsoncolortransparencyin4He(e,e′p)scattering,whicharealsofeasibleatCEBAF.In1994,wecanmakemorereliableprojectionsintofuturebecauseourunderstandingoftheonsetofcolortransparencyhasgreatlybeenaugmentedbytwoexperimentscompletedin1993:i)noeﬀectofCTwasseenintheSLACNE18experimentonA(e,e′p)scatteringatvirtu-alitiesoftheexchangedphotonQ2∼<7GeV2,ii)strongsignalofCTwasobservedintheFNALE665experimentonexclusiveρ0-mesonproductionindeepinelasticscatteringinthesamerangeofQ2.

WediscusstheimpactoftheseobservationsontheCEBAFexperimentalprogram.Wearguetheybotharegoodnews,bothwereanticipatedtheoretically,andbothruleinthecorrectQCDmechanismoftheonsetofCT.

∗)PresentedbyNNNattheWorkshoponCEBAFatHigherEnergies

CEBAF,14-16April1994

11IntroductionThefundamentalpredictionofQCDisthatthequarkconﬁgurationswithsmalltransversesize󰁃rhavesmallinteractioncrosssection[1],whichwasdubbedcolortransparency(CT)[2].LookingforCTislongdiscussedasthecaseforthehigh-luminocity,high-dutycycle,(10-20)GeVelectronfacility,whichiswelldocumentedintheELFEproject[3](ELFE=EuropeanLaboratoryforElectrons).Inthemeantime,thegoodnewsfromCEBAFisapossibilityofthe(8-12)GeVupgrade,whichopensexcitingpossibilitiesofdoingCTphysicsatCEBAF.CEBAFisahigh-luminocityfactoryofvirtualphotons.HigherenergymeansahighervirtualityQ2ofphotons,andhigherQ2meansthatsmallersizesarebecomingaccessiblereachingeventuallyintotheperturbativeQCDregion.Higherenergyalsomeanslongerlifetimeofthesesmall-sizestates.However,fromtheverystart,wemustemphasizethatasfarasCTphysicsisconcerned,thepurelyperturbativeregionlieswellbeyondthekinemat-icalrangeofCEBAFexperimentsonexclusiveprocesses,evenafterthe(8-12)GeVenergyupgrade.TestingthepurelyperturbativeQCDtofewdecimalplacesisataskofinclusiveexperimentsatsuperhighenergyfacilitieslikeLEPorHERA.EvenatLEPandHERA,thepredictivepowerofthepurelyperturbativeQCDrapidlydeteriorateswhentheexclusiveprocessesareconsidered.TherealtaskoftheCEBAFexperimentsistouncovernewQCDphenomenainexclusivereactionsattheinterfaceoftheperturbativeandnonperturbativeQCD.Veryconservativeconclusionofthisoverviewisthattheenergy-upgradedCEBAFshalldothejob.BeforejumpingintoconclusionsonthefeasibilityofCTphysicsatCEBAF,onemustrecallandcriticallysummarizetheresultsofthetwoCTexperimentscompletedin1993:

•TheA(e,e′p)reactionontheD,C,FeandAutargetswasstudiedbytheSLACNE18collaborationwiththenegativeresult:noCTeﬀectsareseenatQ2≤7GeV2[4].

•TheFNALE665experiment[5]onexclusiveproductionoftheρ0mesonsindeepinelasticscatteringofmuonsonnucleiproducedasolidevidenceforCTinpreciselythesamerangeofQ2asexploredintheNE18experiment.

TheearlyhistoryofCTfocusedonthequasielasticA(e,e′p)scatteringofelectronsonnuclei.AnumberofpredictionsofprecociousCTatlowQ2werepublished(forthereviewandreferencessee[6]),andthefailuretoconﬁrmthisprecociousCTintheNE18experimentconsiderablydampenedthewholesubjectofCT.Fortunately,moreconsistenttreatmentratherpredictedaveryslowonsetofCTintheA(e,e′p)scattering[7,8].Asamatteroffact,theNE18resultsdoperfectlyconﬁrmthecorrecttheoryandruleinthemechanismofCT,whichisaliveandwell,andwecanjoyfullyreciteMarkTwain’stelegramtotheAssociatedPress:”Thereportsofmydeathwereanexaggeration”.TheparalleldevelopmentwasatheoryofCTin(virtual)photoproductionofvectormesonsγ∗N→VN.Fromthetheoreticalpointofview,thisisamuchcleanercase,withawellunderstoodshrinkageofthetransversesizeofthevirtualphotonwiththeincreaseofQ2[9,10].Theprediction[9],notapostdiction,oftheprecociousonsetofCTwasconﬁrmedbytheFNALE665experiment[5],whichputtheCTphysicsintherightperspective.Thestrongpointwhichwewishtomakeinthisreviewisthataftertheenergyupgrade,CEBAFexperimentsonexclusiveelectroproductionofvectormesonscansigniﬁcantlycon-tributetoourunderstandingoftheonsetofCT.Furthermore,theexperimentsonproduc-tionoftheradiallyexcitedvectormesonswillopenanentirelynewwindownotonlyonthe