Wave-packet propagation study of the early-time non-adiabatic dissociation dynamics of NH3Cl: Diabatic picture, effects of isotope substitution and varying the initial vibration levels

Abstract

Reduced two-dimensional (2D) diabatic potential energy surfaces (PESs) of the two lowest electronic states of NH3Cl were constructed by using the adiabatic 2D PESs, and the early-time dissociation dynamics of the charge-transferred excited electronic state of NH3Cl (Ronen et al. in Phys Rev Lett 93: 048301, (2)004) were investigated. In the diabatic representation, it was shown that the dissociation path from H2NH+-Cl- to H2N + HCl includes two different processes: the one-step dynamics of diabatic proton transfer followed by electron adjustment, and the two-step dynamics consisting of firstly electron transfer from the other direction mediated (stimulated) by proton movement to form the ground electronic state of H2NH-Cl and then secondly adiabatic H atom tunneling to H2N-HCl. In order to find a means of controlling the branching ratio of the two paths toward the H2N + HCl and H2NH + Cl limits, the effects of varying the initial vibration levels of the precursor anion NH3Cl- and those of isotope substitution (H2NDCl) were also studied. Only the H2N + HCl limit was observed regardless of the initial vibration level and isotope substitution. The overall features of the dynamics are almost unchanged by deuterium substitution (H2NDCl); only the timescale is increased, as expected.