An angle-resolved mass-spectrometric study of non-dissociating excited states of CS +2 formed in 5 keV collisions of CS +2 with rare-gas targets

Abstract

High-resolution energy-loss spectra were obtained for 5 keV CS + 2 ions scattered through selected angles within the range 0–0.52° following collisions with rare-gas target atoms. Excitation to CS + 2 ( A ) and CS + 2 ( B ) electronic states was clearly observed for all of the five targets used and relative differential cross-sections constructed for each process. From these, integrated cross-sections and most-probable centre-of-mass frame scatter angles, Θ c, were determined. The former increase across the series He to Xe whilst the latter decrease, both trends suggesting that collisions occur with increasingly larger values of impact parameter across this series. The most-probable scatter angles, θ c, in the laboratory frame were largest for a neon target and least for helium and also increase with increasing endothermicity of reaction. If such values (typically 0.1–0.3°) represent lower limits for the θ c values associated with excitation to dissociating states of CS + 2, then collisional scattering will not be negligible in relation to fragmentation scattering in CID experiments involving this molecular ion.