title: On the formation of SFn (-) (n = 1-6) anions via a novel route and their properties.
abstract: BACKGROUND
  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.
authors.affiliation: Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
authors.forename: Rupali
authors.initials: R
authors.lastname: Mane
authors.affiliation: Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
authors.forename: Nitin
authors.initials: N
authors.lastname: Mehrotra
authors.affiliation: Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai, 400085, India.|Homi Bhabha National Institute, Training School Complex, Mumbai, 400094, India.
authors.forename: Dilip K
authors.initials: DK
authors.lastname: Maity
authors.affiliation: Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
authors.forename: Anit K
authors.initials: AK
authors.lastname: Gupta