Ab initio calculation of (2+1) resonance enhanced multiphoton ionization spectra and lifetimes of the (D,3)(2)Sigma(-) states of OH and OD

摘要

High-level ab initio potential-energy curves and transition dipole moments for the OH X (2)Pi, 2 (2)Pi, 1 (2)Sigma(-), D (2)Sigma(-), 3 (2)Sigma(-), A (2)Sigma(+), B (2)Sigma(+), 1 (2)Delta, 1 (4)Sigma(-), and 1 (4)Pi states are computed. The results are used to estimate the (2+1) resonance enhanced multiphoton ionization spectrum for the (D,3)(2)Sigma(-)(v('))<-X-2h nu (2)Pi(v") transitions, which are compared with experiments by Greenslade [see M. E. Greenslade, M. I. Lester, D. C. Radenovic, J. A. van Roij, and D. H. Parker, J. Chem. Phys. 123, 074309 (2005), preceeding paper]. We use the discrete variable representation-absorbing boundary condition method to incorporate the effect of the dissociative intermediate 1 (2)Sigma(-) state. We obtain qualitative agreement with experiment for the line strengths. Radiative and predissociative decay rates of the Rydberg (D,3)(2)Sigma(-) states of OH and OD were computed, including spin-orbit coupling effects and the effect of spin-electronic and gyroscopic coupling. We show that the lifetime of the Rydberg (2)Sigma(-) states for rotationally cold molecules is limited mainly by predissociation caused by spin-orbit coupling. (c) 2005 American Institute of Physics.