Direct Measurement of the Lifetimes and Predissociation Probabilities for Rotational Levels of the OH and OD A² SIGMA+ States

Quantitative measurements for the lifetimes and predissociation probabilities for the F1 and F2 components for individual rotational lines of the A 2 + state for the OH and OD molecules are obtained from absolute phase-shift measurements. It is found that the lifetimes of the F1 and F2 components show effects from a series of predissociations and from mixing with the ground state. The comparison of our individual rotational-line lifetimes with those found in the Hanle effect now show good agreement. Astrophysical implications of preassociation in OH are indicated.