State to state rotational transfer in collisions between IF molecules and helium atoms

Abstract

We report measurements of the rate for transfer of population between rotational levels of the B state of iodine monofluoride in collisions with helium atoms. The measured rates are much larger than those observed for transfer of population between vibrational levels, indicating that the rotational population distribution in the collisionally pumped IF laser should be rapidly thermalized. The rates show a dependence on the quantum number of the initial level, in contrast to the results of theoretical calculations.