Absolute cross-sections of fragment negative ions in electron collisions with difluoromethane

TL;DR

This study measures the absolute cross-sections of negative fragment ions produced by electron collisions with difluoromethane, revealing new resonance features and the coexistence of DEA and IPD processes near 11 eV.

Contribution

First measurement of absolute cross-section for F$^-$ ions in electron collisions with difluoromethane, identifying multiple resonances and simultaneous DEA and IPD processes.

Findings

Detected three fragment anions in DEA range.

Measured absolute cross-section for F$^-$ for the first time.

Observed resonances for F$^-$, CHF$^-$, and F$_2^-$ ions.

Abstract

Dissociative electron attachment (DEA) and ion-pair dissociation (IPD) processes of Difluoromethane (CH$_2$F$_2$) have been studied in the incident electron energy range 0 to 45 eV. Three different fragment anions (F$^-$, CHF$^-$ and F$_2^-$) are detected in the DEA range and two anions (F$^-$ and CHF$^-$) are detected in IPD range. Absolute cross-section of the F$^-$ fragment ion is measured for the first time. Three different resonances for both F$^-$ and CHF$^-$ ions and one single resonance peak for the F$_2^-$ ions are observed. Constant increase in ion counts above 8 eV incident electron energy indicates the involvement of IPD process. From the experimental observation, it is speculated that near 11 eV incident electron energy both DEA and IPD processes occur simultaneously.