On the formation of SFn– (n = 1–6) anions via a novel route and their properties. (8th June 2015)

• Record Type: Journal Article
• Authors: Mane, Rupali; Mehrotra, Nitin; Maity, Dilip K.; Gupta, Anit K.
• Is Part Of: Rapid communications in mass spectrometry. Volume 29:Number 14(2015)
• Page Start: 1317
• Page End: 1327
• Publication Date: 2015-06-08
• Subjects: Mass spectrometry -- Periodicals; 543.65
• DOI: 10.1002/rcm.7225
• Languages: English
• ISSNs: 0951-4198

Abstract

Abstract : Rationale: Sulfur hexafluoride (SF6 ) being a potential greenhouse gas, coupled with its numerous applications, makes the study of the formation and fragmentation of SF6 ‐based species important. The formation of SF6 ‐based anionic species has been studied using the gas feed‐sputtering route and the mechanisms at play during the sputter‐ejection of guest molecule‐derived particles have also been probed. Methods: Studies of the formation of SFn – (n = 1–6) anions were conducted from various surfaces (metal and compound) that were subjected to Cs + ion sputtering in the presence of SF6 gas employing the gas feed‐cesium sputter technique. The anions generated were mass analyzed using a double‐focusing magnetic sector mass spectrometer. Quantum mechanical computations were performed to study the ground state structure and stability of neutral and negatively charged SFn (n = 1–6) systems applying density functional theory (DFT) and ab initio methods (MP2 and CC). Results: This technique readily generated 32 SFn – (n = 1–6) anions for all sizes of 'n' with practicable yields. Mass spectrometric measurements of the yield of sputter‐ejected 32 SFn – (n = 1–6) anions reveal an oscillatory pattern as a function of 'n', with odd values of 'n' being relatively more abundant. The relative yield of 34 SFn – (n = 1–6) anions with respect to size was also measured albeit with low signal intensity. Also observed were F –, S –, F2 –, 33 SF5 – and 33 SF6 – anionic species. The relevant electron affinity and bond dissociation energy (BDE) values were also computed. Conclusions: Gas‐phase SFn – (n = 1–6) anions can be effectively generated by using the gas spray‐cesium sputter technique. Both experimental measurements and calculations indicate the existence of odd–even oscillations in the stability and electronic structure of the SFn (n = 1–6) systems. The highest yield recorded was for the sputter‐ejected SF5 – species and this may be attributed to its 'superhalogen' anionic character coupled with the relatively favorable F 0 fragmentation pathway of sputtered SF6 – . A signature pertaining to intact SF6 – anion ejection is also observed. Copyright © 2015 John Wiley & Sons, Ltd.