Electron attachment to SF6 and lifetimes of SF6- negative ions

TL;DR

This paper models low-energy electron attachment to SF6, accurately describing cross sections, estimating vibrational resonance widths, and analyzing negative ion lifetimes and decay behaviors.

Contribution

It extends existing models to better match experimental data and provides new insights into vibrational resonance widths and negative ion lifetimes.

Findings

Accurate electron attachment cross section modeling

Estimated vibrational Feshbach resonance widths

Analyzed nonexponential decay in SF6-

Abstract

We study the process of low-energy electron capture by the SF6 molecule. Our approach is based on the model of Gauyacq and Herzenberg [J. Phys. B 17, 1155 (1984)] in which the electron motion is coupled to the fully symmetric vibrational mode through a weakly bound or virtual s state. By tuning the two free parameters of the model, we achieve an accurate description of the measured electron attachment cross section and good agreement with vibrational excitation cross sections of the fully symmetric mode. An extension of the model provides a limit on the characteristic time of intramolecular vibrational relaxation in highly-excited SF6-. By evaluating the total vibrational spectrum density of SF6-, we estimate the widths of the vibrational Feshbach resonances of the long-lived negative ion. We also analyse the possible distribution of the widths and its effect on the lifetime measurements, and investigate nonexponential decay features in metastable SF6-.