The fragmentation of SF6 under O- and Al- negative ion impact

摘要

The fragmentation of SF6 under 15-30 keV O- and 20-30 keV Al- impact has been studied using a crossed beam technique. The recoil ions and ion pairs are identified in coincidence with scattered projectiles with different charge states by the usage of time-of-flight (TOF) mass spectroscopy. The yield ratios of fragment ions to SF5+ and the yield ratios of ion pairs to (S+, F+) in collision with O- and Al- are obtained and compared with those of H- and C-. It is found that the ratios have a very strong dependence on the momenta of the projectiles. Besides, by analyzing the TOF spectra, it is also found that more SFn+ with n odd are produced than those with n even under O- , Al- impact, which also happened in collision with H- and C-, positive ion and electron impact. The dissociation channels of SFn2+ are found to be insensitive to incident ions' energy and kind in our energy range.