Rotational influence on multiphoton absorption efficiency in SF₆-N₂ mixtures

Abstract
The results of pulsed IR photoacoustic spectroscopy measurements of multiphoton absorption and rotational relaxation processes in SF₆-N₂ mixtures are presented. Total average number ( ) of absorbed photons per one absorbing molecule (SF₆) during the laser pulse was compared with average number of absorbed photons ( ) really stored in SF₆ vibrational modes, using generalized coupled two-level model. Obtained results can be used to confirm or predict the excitation level ( ) of absorbing molecule during the laser pulse, as a function of added buffer-gases. This approach could allow one to control laser field - molecule interaction in different gas mixtures, understand the efficiency of collisional effects (especially rotational relaxation) and their positive and negative influence on absorption characteristics of irradiated polyatomic molecule.