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

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.