The optical spectra of gaseous and solid SF6 in the extreme ultraviolet and soft x-ray region

Fragmentation of Energy-Selected SF5CF3+ Probed by Threshold Photoelectron Photoion Coincidence Spectroscopy: Bond Dissociation Energy of SF5-CF3 and Its Atmospheric Implications

“…Using tunable VUV radiation from a synchrotron source and threshold photoion-photoelectron coincidence spectroscopy, we have studied the fragmentation of the valence states of SF 5 42 This type of reaction is just one of several bimolecular processes which could remove this molecule from the atmosphere. Indeed, the electron attachment data strongly suggest that dissociative electron attachment is the dominant removal process.…”

“…To validate the method for determining the first DIE of SF 5 shows the threshold photoelectron spectrum (TPES) of CF 4 over the energy range 15.5 to 18.8 eV. The KE data were extracted from the multiple TOF spectra by the simplified way described in section 4.…”

“…The threshold photoelectron spectrum (TPES) of SF 5 The broad peak at 16.94 eV, ca. 2.7 eV above the ground state, probably corresponds to several bands produced by removal of a F 2pπ non-bonding electron.…”

“…6 If the bond strength is rather greater, then the removal of SF 5 CF 3 from the atmosphere will, like CF 4 and SF 6 , be governed by ionic or vacuum-UV processes occurring in the mesosphere. 7 We report a study of the fragmentation of the parent cation of SF 5 The parent cations of CF 4 , SF 6 and SF 5 CF 3 have the common property that the parent ion is not observed in a conventional 70 eV electron-impact mass spectrum. 11 In other words, the ground electronic state of these cations is repulsive in the Franck-Condon region, dissociating on a timescale that is very much faster than the transit time of the ion through a magnetic or quadrupole mass spectrometer.…”

“…The implication of this bond strength is that SF 5 CF 3 is very unlikely to be broken down by UV radiation in the stratosphere. In addition, over the complete energy range of 12-26 eV, coincidence ion yields of SF 5 4 and SF 6 , respectively, so that fragmentation of SF 5 CF 3 + to these ions involves migration of a fluorine atom across the S−C bond.…”