Investigation of multiphoton absorption in SF6by third harmonic generation

In a series of third harmonic generation experiments, we are able to probe the excitation of SF6molecules through the discrete states below 3000 cm^-1. The nonlinear susceptibility of SF6is strongly affected by multiphoton resonances and by population redistribution and depletion. The third harmonic generation spectrum for SF6was measured for intensities above and below the molecular dissociation threshold. Experimental evidence indicates the presence of several resonant multiphoton transitions in the discrete states and one and two-photon transitions from discrete states to the quasi-continuum, depending on the frequency of laser excitation.