Energy transfer in kiloelectronvolt collisional activation determined from relative yields and translational energies of fragment ions formed in collision activated decomposion of CH +4 ions

Abstract

Relative yields of product ions from collision activated dissociation of 3 or 8 KeV CH + 4 ions with He, Ar or CH 4 target gas have been measured under conditions in which scattering losses are observed to be negligible. Scatter profiles indicate that scattering is more extensive for the higher energy requirement product ions C + and CH + (and H +), which explains why previous comparable spectra show smaller relative yields of these ions than do the present spectra. The efficiencies of the CAD reactions are also larger than previously observed and approach 40% for He target gas. Parent ion translational energy losses associated with each fragment ion type have also been measured and these values, coupled with the relative yield values, allow derivation of energy transfer functions in an approximate form. These functions, which vary with target gas and with collision energy, are associated with mean energy transfers of up to about 13 eV and show significant energy tailing into the 20–50 eV range, this being due in part to target particle excitation occurring concurrently with excitation of the projectile ion.