Average Doppler Shift of Gamma-ray Spectra of Positron Annihilation Process in Molecules

TL;DR

This study introduces the Average Doppler Shift (ADS) as a new physical quantity to characterize gamma-ray spectra from positron annihilation in molecules, revealing linear correlations with valence electron energy and spectral width.

Contribution

The paper defines ADS and demonstrates its linear relationship with valence electron energy and FWHM, offering a new approach to analyze positron annihilation spectra.

Findings

ADS correlates linearly with valence electron energy.

ADS has a linear relationship with FWHM.

Annihilation predominantly occurs on valence electrons.

Abstract

This paper studies the gamma-ray spectra of positron annihilation processes in a series of molecules. The results show that the average valence electron energy of the molecules has a linear correlation with the full width at half maximum (FWHM) of the gamma-ray spectra. In addition, we defined a new physical quantity Average Doppler Shift (ADS), which can be used as the eigenvalue to describe the characteristics of the gamma-ray spectra. Since ADS contains all the information about the gamma-ray spectra, it can more accurately represent the characteristics of the gamma-ray spectra. For a series of molecules, this paper compares the ADS and FWHM of their gamma-ray spectra and the average valence electron energy. The results show that ADS has a linear correlation with the average valence electron energy and the FWHM. Further, this proves that the annihilation mainly occurs on valence electrons, and it also illustrates that the ADS has certain applicability. It is expected that this will provide us with a deeper understanding of the positron annihilation process.