ENERGY EFFECTS IN COLLISIONAL NEUTRALIZATION WITH ORGANIC-MOLECULES

Neutralization-reionization of CH3OH+., CH3NH2+. and (CH3)(2)NH+. ions was studied under conditions of exothermic and endothermic electron t ransfer and distributions of internal energy in the reionized ions wer e determined. The internal energy deposited on neutralization at kiloe lectronvolt collision energies is governed by Franck-Condon effects fo r the systems under study, whereas the endothermic or exothermic energ y balance in electron transfer from molecular targets has only a small effect on the high-energy fraction of the molecules formed Electron t ransfer from low-lying molecular orbitals of the organic donor is sugg ested to occur during random orientations of the ion-molecule collisio n pair. The internal energy of the precursor ions to be neutralized ha s a large effect on the relative abundances of survivor ions in the sp ectre. Vertical recombination energies of CH3OH+. and CH3NH2+. are fou nd by Gaussian-2 level calculations to differ substantially from verti cal ionization energies of the corresponding neutral molecules. Franck -Condon effects are analyzed for the vibrational modes that are affect ed most by vertical electron transfer.