PULSED PHOTOACOUSTIC STUDY OF COLLISIONAL EFFECTS IN IR MULTIPHOTON ABSORPTION-MEASUREMENTS

The pulsed laser photoacoustic technique, simultaneously used with tra nsmission spectroscopy, was applied for detailed study of IR multiphot on absorption processes in polyatomic molecules. Collisional effects w ere specially investigated in SF6 diluted with Ar as nonabsorbing spec ies. The results regarding the enhanced absorption cross sections (sig ma(e)) for SF6-Ar mixtures are obtained with precision of +/-18 - +/-2 9%. The differential absorption cross sections (sigma(d)e), as well as the average number of absorbed photons [n] per SF6 molecule in 0, 1 - 0,7 J/cm2 fluence range and 1 - 140 mbar Ar pressure range are also p resented.