Vibrational and rotational energy transfer in collisions of vibrationally excited HF molecules with Ar atoms

Abstract

This work presents converged vibrational close coupling-rotational coupled states calculations of cross sections and rate constants for rotational and vibrational transitions in collisions of vibrationally excited HF molecules with Ar atoms. Reduced channel basis sets assuming both a lower and an upper cutoff in vibrational quantum number are used for calculations at high internal energies of the diatomic molecule. The most recent potential energy surface is employed for the calculations and the correspondence of the results to the previous investigation of rovibrational dynamics in collisions of HF(v=1) with Ar is examined. It is shown that initial vibrational excitation stimulates vibrationally inelastic transitions to a great extent while the rotational energy transfer is essentially unaffected by initial v-number. The cross sections for vibrational relaxation of different vibrational levels of HF are shown to exhibit a strong dependence on initial rotational energy which is, however, of different magnitude for different vibrational states. The dependence of the vibrational relaxation of HF(v=1,3,6) on the translational energy of the atomic collision partner is different by an energy independent factor for different vibrational levels in the high energy limit and shows minima at low collision energies.