Low Energy Positron Diffraction and Positron Re-emission Microscopy Experiments

布兰迪斯大学的高亮度正电子束被用于进行低能正电子衍射（LEPD）和正电子再发射显微镜（PRM）实验。LEPD技术可以提供比其电子对应的低能量电子衍射（LEED）更精确的化合物半导体表面结构测定。所提出的实验旨在将目前80 nm的空间分辨率扩展到1nm。将研究化合物半导体和金属表面。PRM将产生放大5万倍的正电子图像，这些正电子以低能量从Ni（100）薄膜中反射出来。低能量正电子对亚表面缺陷和上覆原子的极端敏感性和非破坏性将用于成像特征，如亚单层金属薄膜生长中的单空位和界面缺陷，这些是传统电子显微镜无法看到的。

The high brightness positron beam at Brandeis University is being used to perform low energy positron diffraction (LEPD) and positron reemission microscope (PRM) experiments. The LEPD technique can provide a more precise structural determination of compound semiconductor surfaces than its electron counterpart, low energy electron diffraction (LEED). The proposed experiments are designed to extend the present 80 nm spatial resolution to 1nm. Compound semiconductors and metal surfaces will be investigated. The PRM will produce up to 50,000x magnified image of positrons reemitted at low energies from a thin Ni(100) film. The extreme sensitivity and nondestructiveness of low energy positrons to subsurface defects and overlying atoms will be used for imaging features, such as monovacancies an interfacial defects in submonolayer metal film growth, that can not be seen with conventional electron microscopy.