原子級空間解析之電子激發能譜檢測技術與其在奈米材料之應用

Studies of Electronic Excitations in Nano-Materials by Spatially Resolved Electron Energy Loss Spectroscopy

隨著日新月異的科學研究發展，嶄新的高解析場發射掃描穿透式電子顯微鏡在加裝球差補償修正器與單色器後，對於200 KV的加速電子，已能達到0.1 nm以下的空間高解析度與0.2 eV以下之能量高解析度。在同時加載X射線能譜儀和電子能損失能譜儀之下，可執行原子級尺度的點、線、面之電子激發分析。並將可進行諸如晶體結構、高解析週期性相位對比之晶格影像、高解析原子序對比影像、電子結構、成分與化學鍵結分析等等。 The electronic excitations of nano-materials are investigated by spatially resolved electron energy loss spectroscopy and energy dispersive X-ray spectrometer used in conjunction with scanning transmission electron microscopy(STEM-EELS/EDS) in order to further study the microstructure, physical and chemical properties. When fast electrons pass through the materials, they will generate various solid state excitations with bulk and surface characteristics via Coulomb interactions and lose energies accordingly. Typical bulk excitations include bulk plasmons(BPs) , Cherenkov radiations, band gap and inter band transitions and inner-shell ionizations. Surface excitations with propagation wavevector confi ned along the surface include surface plasmons(SPs) , surface guided mode and surface exciton polaritons(SEPs) . These excitations play a very important role in the properties of materials.