Knowledge Bank

Transition probabilities have been calculated as a function of vibrational and rotational level for the $A2\Sigma +-X2\Pi j$ system of the hydroxyl molecule. The wavefunctions are obtained from RKR calculations using a program furnished to us by R-N- Zare. At low internuclear distance r, the electronic transition moment $Re$(r) has been previously $shown1$ to have a linear form. To this is added a hyperbolic tail at large r, patterned after \emph{ab initio} $calculations2$ on these electronic stales. The two needed parameters are obtained by comparison with previously determined experimental $data1$. The results show as anticipated, a variation in transition probability with rotational quantum number J, the degree of which varies with vibrational band. The widely used results of Anketell and $Learner3$, based on an exponential form of the transition moment, are accurate to within about 10% over the range N = 0 to 20 within a given band, but are not correct from band to band.