TUNABLE DIODE LASER STUDIES OF COLLISIONLESS INFRARED EXCITATION OF SF₆ AND NH₃ MOLECULES

Abstract
The work was aimed at the study of collisionless excitation of molecules by intensive laser infrared (IR) radiation. Molecules of SF₆ and NH₃ were cooled in a pulsed supersonic jet. Excitation was provided by various lines of a TEA CO₂ laser. A tunable diode laser was used for probing of molecules. The dependences have been obtained for the fraction f of molecules excited from individual rotational levels on the density Φ of the excitation energy [1-5]. A model of the laser field is proposed which gives a good description of f (Φ) in the case of one- and two-photon excitation of NH₃ [5]. It is believed that the present model will describe appropriately IR excitation of molecules of SF₆ type in the region of lower discrete vibrational levels.