Multiphoton Dissociation of Sulfur Hexafluoride in a Vibrationally Cooled Compression Shock

Abstract

Multiphoton IR dissociation of SF6 (in a mixture with CH4) under nonequilibrium conditions of a compression shock formed by an intense, gas dynamically cooled, pulsed molecular beam impacting a solid surface was studied using the HF* luminescence detection (λ ≅ 2.5 μm) technique. The dependences of the HF* luminescence intensity on the distance Δx between the region in which molecules were excited and the surface and on the laser radiation frequency at different values of Δx were obtained. It was shown that, as the distance Δx decreased from ≅4 to 1.5 mm, the HF* luminescence intensity increased by more than an order of magnitude as compared to the case of excitation of molecules in an undisturbed flow, whereas the frequency dependences of luminescence intensity (SF6 dissociation yield) were broadened only insignificantly.