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

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 I3γ, defined as o-Ps self-decay intensity, was used to analyze Ag layer capped and non-capped silica aerogel by slow positron annihilation Doppler -broadening spectroscopy. The result shows that I3γ can provide more information for researching mesoporous material and nanometer film.