Diode laser studies of SF6 and NH3 molecules excited by intense IR radiation

ABSTRACT During last years we have studied the dynamics of collisionless SF6 and NH3 molecules' excitation by TEA CO2 laserradiation. The main purpose of these researches was to explain why the molecules, which have no exact resonance with the Co2 laser field absorb one or several JR quanta. We made measurements in a free supersonic jet and in a cell. Excitingenergy densities were among icr2 d 2.0 J cm2. The fraction of molecules excited from individual rotational levels was measured and its dependences on the CO2 laser frequency and on the energy density were investigated. We will present thecomparison of the experimental data with theoretical calculations, and questions that still remain unclear will be discussed. 1. INTRODUCTIONIn the present paper our investigations of a few years are reviewed. The subject of the investigations was collisionlessexcitation of molecules by intensive laser JR radiation. Our interest to this problem stems from the fact that up to now no model has been developed to simulate multiphoton excitation (MPE) of molecules by intensive laser JR radiation that couldadequately describe experimental results.Numerous experiments performed since early '70-ies have shown that collisionless MPE and dissociation in the fields of