Knowledge Bank

The lifetimes of the Individual vibrational-rotational level of the $A2\Sigma +$ state of OH(OD) have been determined theoretically. Contributions from both radiative and non-radiative (pre-dissociative) processes are considered, Potential energy curves are presented for the $X2\Pi$ and $A2\Sigma +$ bound states and the $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}\Sigma -,2\Sigma -$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi$ repulsive states. These potential curves were generated from self-consistent-field plus configuration-interaction calculations using both a near Hartree-Fock Slater basis and a DZP Cartesian gaussian basis. Results for the electronic transition moment between the X and A states, and the spin-orbit matrix elements between the A state and the repulsive states as a Function of internuclear distance are presented. Computed lifetimes are in good agreement with experiment. It is conclusively shown that the $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}\Sigma -$ state accounts for the weak predissociation in the v = 0-2 vibrational levels while the $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}\Pi$ state is principally responsible for the much stronger predissotiation in the higher vibrational levels. Comparison of experiment and theory provides a good estimate of the crossing points of the rotation less potentials.