透射电镜电子能量损失振动谱的研究进展

近年来,透射电子显微镜在球差矫正器、单色仪等方面取得了长足的发展,使得它在材料科学和凝聚态物理等研究中发挥越来越大的作用。本文简要介绍近十年透射电子显微镜电子能量损失谱技术在声子物理研究方面的进展。目前,基于这一技术,可以开展实空间和倒空间同时分辨的电子能量损失谱测量(简称四维电子能量损失谱,4D-EELS),在纳米尺度上绘制空间分辨声子色散分布图;能实现原子尺度上声子谱的测量,得到声子态密度的信息。此外,电子散射在能量匹配、动量匹配方面都与光子散射有很强的互补性,因此为声子极化激元的测量提供了一个新的手段。最后,本文简要展望电镜能损振动谱的研究前景。

Recent Progress of Vibrational Electron Energy-Loss Spectroscopy in Scanning Transmission Electron Microscope

With the recent developments of dedicated aberration correctors and monochromators, scanning transmission electron microscopes(STEMs) are playing an increasingly important role in condensed matter physics and materials science.Here, we review the progress of vibrational electron energy-loss spectroscopy(EELS) in STEM in the past decade.The technique termed four-dimensional EELS(4 D-EELS) has made it possible to probe lattice dynamics with both nanometer spatial resolution and fine momentum resolution.High spatial resolution in STEMs also enables atomically-resolved vibrational measurements to extract the local projected density of states(PDOS).Besides, electron scattering offers a large momentum transfer and a wide detection spectral range, providing new opportunities to investigate phonon polaritons complementary to conventional optical methods.Finally, prospects for future developments of vibrational STEM-EELS studies are also discussed.