Negative photoion spectroscopy of SF6 in the inner valence and S 2p energy regions

Abstract

Negative fragment ion formation from SF6 has been studied using synchrotron radiation within the energy range 20-205 eV. The fragment ions F-, F2-, S- and SF- have been observed. It is shown that shape resonance and unoccupied valence orbitals play an important role in negative ion formation after photoexcitation of inner valence and S 2p electrons. The negative ion yields after photoexcitation of a S 2p core electron show evidence of localization of the shape resonance orbitals around the central S atom. The yields of F- and F2- in the outer valence and inner valence energy regions not only confirm that ion pair formation occurs via predissociating Rydberg states but also demonstrate, for the first time, the importance of intravalence transitions.

Vacuum Ultraviolet Negative Photoion Spectroscopy of SF6, CF4 and SF5CF3

“…F -and CF 4 into CF 3 + ? F -has been studied previously by Mitsuke et al [21,22] and Scully et al [23]. The results presented here have seen a much larger number of anions than observed by these groups, and the data of Mitsuke et al has allowed the SF 5 CF 3 data to be put on an absolute scale (as outlined in Sect.…”

Vacuum-UV negative photoion spectroscopy of SF5CF3

“…21,22 Based on Frank-Condon arguments, the latter process is thought to be more common, although significant coupling between Rydberg and ion pair states is a requirement − one which is not always met. 24,25 and Scully et al 26 We have seen a much larger number of anions than observed by these groups, and the data of Mitsuke et al 24,25 has allowed us to put our SF 5 CF 3 data on an absolute scale. To our knowledge this is the first report of ion pair production following VUV photoexcitation of SF 5 CF 3 .…”

“…Finally, it is noted that shape resonances have been observed in the 19 yields of many anions in both SF 6 and CF 4 above 25 eV. 26,31 There is no obvious evidence for such peaks in our ion yields from SF 5 CF 3 , but it would be surprising if they were not present.…”

Two Studies in Gas-Phase Ion Spectroscopy

“…These data are available in the literature for CF 4 [41], SF 6 [42,43], CH 4 [44], CH 3 X (X = F, Cl, Br) [45], C 2 H 4 [46], C 2 H 6 [47,48], C 3 H 8 [47], and the chlorofluoromethanes (CFCl 3 , CF 2 Cl 2 , CF 3 Cl) [49]. The present work is in excellent agreement with these earlier studies and in most cases the quality and quantity of data obtained have improved.…”

“…Results have shown that in most cases, if charge transfer is energetically allowed, it will occur and is usually the dominant reaction channel [34][35][36][37][38][39][40][41][42][43][44][45]. The same experiments have shown that some cations and molecules do not react when the energetics do not allow for charge transfer.…”