Full-Dimensional Quantum Dynamics of Vibrational Mediated Photodissociation of HOD in Its B Band

The photodissociation dynamics for the ground and three fundamental vibrational states of HOD were explored from quantum dynamical calculations including the electronic X̃, Ã, and B̃ states. The calculations were based on a Chebyshev real wave packet method. Due to the different shapes of the initial vibrational wave functions and isotopic effect, the calculated absorption spectra, product state distributions, and branching ratios show different dynamic features. The initial bending excited vibtaional state (0, 1, 0) generates a bimodal behavior on the absorption spectrum and an inverted vibrational population of OD(X̃) fragment at some total energies. The rotational state distributions from four vibrational states have two different behaviors. One has a single broad peak, whereas the other one has a bimodal structure. Large OD(Ã)/OD(X̃) ratios are found for photodissociation from four vibrational states at high total energies, which indicate that the H atom dissociates mainly via the adiabatic pathway. We also calculated the OD/OH isotopic branching ratios from four vibrational states and found that the OD + H production channel is dominant over the OH + D channel in the energy range considered. The calculated results are consistent with the available observed ones.