Effects of molecular rotation and vibration–rotation interaction on collisionless multiple-photon excitation of SF_6

Abstract

The effects of molecular rotation and vibration–rotation interaction and thermally excited vibrational states on the collisionless multiple-photon excitation (CMPE) of SF6 are calculated numerically, using preliminary vibrational anharmonic parameters derived from recent spectroscopic data. This is the first calculation of CMPE in SF6 employing the rotational energy levels and transition moments appropriate for a spherical-top molecule. Our calculated multiphoton threshold for CMPE in SF6 is lower by orders of magnitude than the threshold calculated without rotations. We have also made a tentative assignment of one transition in the ν3 → 2ν3 spectrum of SF6.