4D Scanning Ultrafast Electron Microscopy: Visualization of Materials Surface Dynamics,Journal of the American Chemical Society

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4D Scanning Ultrafast Electron Microscopy: Visualization of Materials Surface Dynamics
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2011-05-25 , DOI: 10.1021/ja2031322
Omar F. Mohammed ₁ , Ding-Shyue Yang ₁ , Samir Kumar Pal ₂ , Ahmed H. Zewail ₁

Affiliation

The continuous electron beam of conventional scanning electron microscopes (SEM) limits the temporal resolution required for the study of ultrafast dynamics of materials surfaces. Here, we report the development of scanning ultrafast electron microscopy (S-UEM) as a time-resolved method with resolutions in both space and time. The approach is demonstrated in the investigation of the dynamics of semiconducting and metallic materials visualized using secondary-electron images and backscattering electron diffraction patterns. For probing, the electron packet was photogenerated from the sharp field-emitter tip of the microscope with a very low number of electrons in order to suppress space-charge repulsion between electrons and reach the ultrashort temporal resolution, an improvement of orders of magnitude when compared to the traditional beam-blanking method. Moreover, the spatial resolution of SEM is maintained, thus enabling spatiotemporal visualization of surface dynamics following the initiation of change by femtosecond heating or excitation. We discuss capabilities and potential applications of S-UEM in materials and biological science.

中文翻译：

4D 扫描超快电子显微镜：材料表面动力学的可视化

传统扫描电子显微镜 (SEM) 的连续电子束限制了研究材料表面超快动力学所需的时间分辨率。在这里，我们报告了扫描超快电子显微镜 (S-UEM) 作为一种具有空间和时间分辨率的时间分辨方法的发展。该方法在使用二次电子图像和背散射电子衍射图案可视化的半导体和金属材料的动力学研究中得到了证明。对于探测，电子包是从显微镜的尖锐场发射器尖端光产生的，电子数量非常少，以抑制电子之间的空间电荷排斥并达到超短时间分辨率，与传统的波束消隐方法相比，改进了几个数量级。此外，保持了 SEM 的空间分辨率，从而能够在飞秒加热或激发引发变化后实现表面动力学的时空可视化。我们讨论了 S-UEM 在材料和生物科学中的能力和潜在应用。

更新日期：2011-05-25

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