氧化镁等离激元与价电子激发纳米分辨STEM⁃EELS研究  

Valence electron excitations and plasmon of MgO via STEM⁃EELS

作　　者：杜进隆 赵娜 时若晨 李跃辉 张敬民[1] 徐军[1] 高鹏 DU Jin-long;ZHAO Na;SHI Ruo-chen;LI Yue-hui;ZHANG Jing-ming;XU Jun;GAO Peng(Electron Microscopy Laboratory,School of Physics,Peking University,Beijing 100871;The National Museum of China,Beijing 100006,China)

机构地区：[1]北京大学电子显微镜实验室,北京100871 [2]中国国家博物馆,北京100006

出　　处：《电子显微学报》2022年第5期550-555,共6页Journal of Chinese Electron Microscopy Society

基　　金：国家自然科学基金资助项目(Nos.11974023,12004010,U20B2025);广东省重点领域研发计划项目(Nos.2018B030327001,2018B010109009)。

摘　　要：本文针对单晶面心立方氧化镁样品在low⁃loss电子能量损失谱中等离激元峰和价电子激发峰重合这一问题,利用高能量分辨和空间分辨扫描透射电镜-电子能量损失谱(STEM⁃EELS)技术探索和研究了通过改变样品厚度和利用动量分辨电子能量损失谱技术用来区分单晶氧化镁电子能量损失谱中等离激元和价电子激发信号的可行性。结果表明,对于氧化镁样品,可以通过测量厚度连续变化的电子能量损失谱以分别研究其等离激元和价电子激发。对于样品较厚的情况,由于两种信号的局域性不同,通过测量动量分辨电子能量损失谱,可以有效区分单晶氧化镁价电子激发和等离激元信号。论文研究结果可能适用于在纳米尺度上测量材料的激子、带隙和等离激元等电子能量损失谱研究。For face⁃centered cubic MgO single crystal,plasmon and valence electron excitation peaks are usually overlapped with each other in their low⁃loss electron energy loss spectrum.To distinguish these two peaks,we employed scanning transmission electron microscopy⁃electron energy loss spectroscopy(STEM⁃EELS)technology with nanoscale spatial resolution and high energy resolution.By changing the thickness of a MgO single crystal,we find that the plasmon and valence electron excitations can be distinguished by measuring the EELS of the MgO single crystal.At a relatively thicker location of the MgO single crystal,the two peaks can be effectively distinguished by momentum⁃resolved EELS due to the localized difference of the two signals for the two peaks.Our result may be applicable to explore excitons,band gaps and plasmon of materials at nanoscale.

关 键 词：电子能量损失谱 单晶MgO 等离激元 价电子激发 

分 类 号：TH838[机械工程—仪器科学与技术] O536[机械工程—精密仪器及机械] TG115.215.3[理学—等离子体物理]