Low Energy Positron Diffraction and Positron Re-emission Microscopy Experiments

布兰迪斯大学的高亮度正电子束正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。与低能电子衍射(LEED)技术相比，LEPD技术可以提供更精确的化合物半导体表面结构测定。提出的实验旨在将目前的80 nm空间分辨率扩展到1 nm。将对化合物半导体和金属表面进行研究。PRM将产生高达50,000倍的放大图像，这些图像是从一层薄的Ni(100)薄膜以低能量重新发射的正电子。低能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被用于成像特征，如亚单层金属薄膜生长中的单缺陷和界面缺陷，这是传统电子显微镜所不能看到的。

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.