Gamma-ray spectra of hexane in gas phase and liquid phase

TL;DR

This study compares theoretical and experimental gamma-ray spectra of hexane in gas and liquid phases, revealing phase-dependent electron annihilation behaviors and highlighting the role of positrophilic electrons.

Contribution

First to identify the distinct roles of positrophilic electrons in hexane's gamma-ray spectra across phases, linking molecular orientation and intermolecular interactions.

Findings

Gamma-ray spectra match theory in both phases.

Positrophilic electrons dominate in gas phase.

All valence electrons contribute in liquid phase.

Abstract

Theoretical gamma-ray spectra of molecule hexane have been calculated and compared with the experimental results in both gas (Surko et al, 1997) and liquid (Kerr et al, 1965) phases. The present study reveals that in gas phase not all valence electrons of hexane exhibit the same probability to annihilate a positron. Only the positrophilic electrons in the valence space dominate the gamma-ray spectra, which are in good agreement with the gas phase measurement. When hexane is confined in liquid phase, however, the intermolecular interactions ultimately eliminate the free molecular orientation and selectivity for the positrophilic electrons in the gas phase. As a result, the gamma-ray spectra of hexane become an averaged contribution from all valence electrons, which is again in agreement with liquid phase measurement. The roles of the positrophilic electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study.