正电子湮没多普勒谱中的3γ/2γ分析

Analysis of 3γ/2γ Ratio in the Measurement of Positron Annihilation Doppler-Broadening Spectroscopy

在慢正电子束研究表面的实验中,一般仍使用高纯Geγ谱仪测量正电子湮没多普勒展宽能谱, 对能谱的分析采用线形参数S,W,这些参数提供的信息有限．例如,当电子与正电子在材料中形成电 子偶素时,简单的线形参数非但不能表征它们,反而因它们的存在使得分析变得复杂．本工作在对多普 勒展宽能谱进行数据处理的过程中,引入正态电子偶素自衰变强度I3γ参数,建立了从能谱中获得I3γ 参数值的方法。以标准样品为基准,选用Ag盖帽的气凝硅胶进行I3γ参数计算,工作表明新参数对研究 介孔材料及纳米薄膜能提供更丰富的信息．

Doppler-broadening slow positron annihilation spectroscopy is used to measure the concentration, spatial distribution, and size of open-volume defects in surface and interface of material. In this method, the quantitative evaluation is generally carried out with the line shape parameter S and W, but sometimes the parameters provide some finite information. For example, if positron and electron form positronium （include o-Ps and p-Ps） in material, the parameters S and W may provide little information about positronium even complicate the analyses. A parameter I3-γ, defined as o-Ps selfodecay intensity, was used to analyze Ag layer capped and non-capped silica aerogel by slow positron annihilation Doppler-broadening spectroscopy. The result shows that I3-γ can provide more information for researching mesoporous material and nanometer film.