The influence of vibration-rotation interaction on intensities in the electronic spectra of diatomic molecules I. The hydroxyl radical

Abstract

The effect of vibration-rotation interaction on transition probability is examined in detail for the $^2\sum^+$-$^2\Pi_i$ transition of the hydroxyl radical, using a Morse-Pekeris model. It is shown to have a significant effect on the rotational temperature (of the order of 200$^\circ$ at 3000$^\circ$K) for the (0, 0) band and to be especially important for the (0, 1) band. The variation of transition moment with internuclear distance is examined and an expression of the form R$_e$(r) = constant x e$^{-2.5r}$ where r is the internuclear distance in angstroms is recommended. With this value, corrections are obtained to rotational temperatures and the f value for the Q$_1$(6) line of the (0, 0) band is altered to 1.0 $\pm$ 0.5 x 10$^{-3}$. Calculations for the OD radical are also presented.