Very high critical energy fragmentations observed in CID

High energy CID fragmentations of triatomic alkali halide cluster ions were examined to estimate the energy transfer during the CID process. A detailed CID study using keV collisions revealed that M2X+ clusters yield not only the expected M+ ions but practically all possible combinations of mono- and biatomic ions. In the case of Cs2I+, for example Cs+, Cs2+, CsI+, and even I+ fragment ions are observed. The results suggest that collisional energy transfer in keV collisions has a monotonously decreasing shape (full width at half height is ∼2 eV) and has a long high energy tail extending well over 10 eV (with at least 5% probability), the average collisional energy transfer being about 5 eV.