An investigation of the interaction of intense laser radiation with molecules of sulfur hexafluoride through the buffer gas technique

Measurements of the coefficient of the absorption of intense (approximately 10 to the 7th W/sq cm) radiation from a CO2 laser by SF6 molecules in the presence of noble gases and at pressures up to 40 bars are presented. The dependence of the coefficient of absorption on the pressure and type of buffer gas, as well as on the wavelength and intensity of the incident radiation, makes it possible to follow the formation of the vibrational state distribution function of the molecules. The character of the distribution function depends on the competition between vibrational relaxation processes and laser radiation absorption. At high pressures, that is, at helium pressures greater than approximately 20-40 bars, a two-level scheme for the interaction of intense laser radiation with SF6 is implemented experimentally for the first time. Here, molecules excited by light to the v = 1 state relax instantaneously upon collision. The dependence of the rate constant for the destruction of SF6 molecular states on the number of the vibrational level v upon collision with helium atoms can be evaluated from the experimental data. Taken as a whole, the data confirm the assumption of the linear, single-photon nature of the interaction of laser radiation with SF6 molecules.