Theoretical evidence for nonadiabatic vibrational deexcitation in H2(D2) state-to-state scattering from Cu(100).

Dynamical calculations are presented for electronically nonadiabatic vibrational deexcitation of H2 and D2 in scattering from Cu(111). Both the potential energy surface and the nonadiabatic coupling strength were obtained from density functional calculations. The theoretically predicted magnitude of the deexcitation and its dependence on incident energy and isotope are all in agreement with state-to-state scattering experiments [on Cu(100)], and this gives indirect evidence for a nonadiabatic mechanism of the observed deexcitation. Direct evidence could be obtained by measuring the chemicurrent associated with the deexcitation, and its properties have been predicted.