CO2-Laser Excitation of a Molecular Beam Monitored By Spontaneous Raman Effect

Abstract

The vibrational state populations and rotational temperatures of CF3Br and SF6 have been determined at variable distance from the nozzle XR/D for expanding molecular beams using the spontaneous Raman effect. Moreover, also at variable XE/D the molecular beam has been excited with a tightly focussed C.W. line tunable CO2-laser. The phenomenon of collision assisted absorption and up-pumping of SF6 molecules has been investigated. With XE/D ⋍ 0.5, Raman spectra at XR/D = 4 were observed which correspond to a thermally vibrational heating of the beam. An average vibrational energy equivalent to 6CO2-laser photons could be pumped into the SF6 beam molecules. Excitation with the C02-laser at larger XE/D produced Raman spectra with a preferred v3-mode excitation of the SF6 molecules. Using a predissociation technique, Raman spectra of SF6 clusters have been observed.