A measurement of electron-wall interactions using transmission diffraction from nanofabricated gratings
A measurement of electron-wall interactions using transmission diffraction from nanofabricated gratings
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使用纳米制造光栅的透射衍射测量电子-壁相互作用
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
Herman Batelaana
中科院分区：
文献类型：
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作者：
B. Barwick;G. Gronniger;Lu Yuan;S. Liou;Herman Batelaana
介绍了金属涂层独立纳米光栅的电子衍射，并对电子-光栅相互作用进行了定量路径积分分析。观察到20阶的电子衍射，表明我们的纳米光栅质量高。电子束被离子研磨材料的狭缝准直到它的衍射极限。我们的路径积分分析首先针对单缝电子衍射进行了测试，然后用相同的理论方法进一步扩展到描述光栅衍射。光栅相对于入射电子束的旋转改变了电子和光栅杆之间的有效距离。这样就可以测量电子和光栅之间的像电荷势。发现图像电荷势约为纯电子-金属壁相互作用值的15%。我们改变了电子能量从50ev到900ev。相互作用时间是典型金属像电荷响应时间的数量级，原则上允许研究像电荷的形成。除了像电荷的相互作用外，还有一个减少电子波横向相干长度的减相过程。脱相过程引起衍射峰的展宽，并与将脱相过程归因于微观接触势的模型相一致。用扫描隧道显微镜观察到的长度尺度约为200nm的表面结构和典型的0.35eV的脱相相互作用强度支持了这一说法。这种脱相模型激发了不同金属涂层的研究，特别是Ni， Ti， Al和不同厚度的Au-Pd涂层。发现Ni的衍射图质量有所提高。这种涂层使能量低至50eV的电子衍射成为可能。这种能量受到我们电子枪设计的限制。这些结果与在低能电子干涉测量中使用这些光栅作为相干分束器特别相关。介绍了金属涂层独立纳米光栅的电子衍射，并对电子-光栅相互作用进行了定量路径积分分析。观察到20阶的电子衍射，表明我们的纳米光栅质量高。电子束被离子研磨材料的狭缝准直到它的衍射极限。我们的路径积分分析首先针对单缝电子衍射进行了测试，然后用相同的理论方法进一步扩展到描述光栅衍射。光栅相对于入射电子束的旋转改变了电子和光栅杆之间的有效距离。这样就可以测量电子和光栅之间的像电荷势。发现图像电荷势约为纯电子-金属壁相互作用值的15%。我们改变了电子能量从50ev到900ev。相互作用时间为典型的金属图像时间数量级。
Electron diffraction from metal coated freestanding nanofabricated gratings is presented, with a quantitative path integral analysis of the electron-grating interactions. Electron diffraction out to the 20th order was observed indicating the high quality of our nanofabricated gratings. The electron beam is collimated to its diffraction limit with ion-milled material slits. Our path integral analysis is first tested against single slit electron diffraction, and then further expanded with the same theoretical approach to describe grating diffraction. Rotation of the grating with respect to the incident electron beam varies the effective distance between the electron and grating bars. This allows the measurement of the image charge potential between the electron and the grating bars. Image charge potentials that were about 15% of the value for that of a pure electron-metal wall interaction were found. We varied the electron energy from 50to900eV. The interaction time is of the order of typical metal image charge response times and in principle allows the investigation of image charge formation. In addition to the image charge interaction there is a dephasing process reducing the transverse coherence length of the electron wave. The dephasing process causes broadening of the diffraction peaks and is consistent with a model that ascribes the dephasing process to microscopic contact potentials. Surface structures with length scales of about 200nm observed with a scanning tunneling microscope, and dephasing interaction strength typical of contact potentials of 0.35eV support this claim. Such a dephasing model motivated the investigation of different metallic coatings, in particular Ni, Ti, Al, and different thickness Au–Pd coatings. Improved quality of diffraction patterns was found for Ni. This coating made electron diffraction possible at energies as low as 50eV. This energy was limited by our electron gun design. These results are particularly relevant for the use of these gratings as coherent beam splitters in low energy electron interferometry.Electron diffraction from metal coated freestanding nanofabricated gratings is presented, with a quantitative path integral analysis of the electron-grating interactions. Electron diffraction out to the 20th order was observed indicating the high quality of our nanofabricated gratings. The electron beam is collimated to its diffraction limit with ion-milled material slits. Our path integral analysis is first tested against single slit electron diffraction, and then further expanded with the same theoretical approach to describe grating diffraction. Rotation of the grating with respect to the incident electron beam varies the effective distance between the electron and grating bars. This allows the measurement of the image charge potential between the electron and the grating bars. Image charge potentials that were about 15% of the value for that of a pure electron-metal wall interaction were found. We varied the electron energy from 50to900eV. The interaction time is of the order of typical metal image ch...