EMPIRICAL-MODEL OF THE STATE-TO-STATE DYNAMICS IN NEAR-RESONANT HYPERTHERMAL X(-TRANSFER REACTIONS()+H2O CHARGE)

H2O+(A) over tilde-(X) over tilde luminescence studies involving X(+) +H2O (X=Ar, N, Kr, N-2) charge-transfer systems are consolidated into an empirical model for the charge-transfer product state distributions associated with hyperthermal collisions of ground-state reactants. Th e model predicts that Franck-Condon active states are populated with a Gaussian vibrational energy distribution that is shifted by approxima tely -0.18 eV with respect to energy resonance. The model is applied t o hyperthermal O+(S-4)+H2O charge-transfer collisions for which lumine scence experiments are too insensitive because weakly emitting vibrati onally excited states of the H2O+<(X)over tilde B-2(1)> State are popu lated. Isotope effects in the O+(S-4)+H2O/D2O charge-transfer cross se ctions are measured using guided-ion beams to test the model. The mode l correctly predicts the observed isotope effect within the hypertherm al collision energy range of 2 and 8 eV.