Pulse photoacoustic technique to study of vibrational relaxation in gases

Characteristic properties of forming of the photoacoustic detector signal at excitation of absorbing gas molecules by a short laser pulse ((tau) vt ) allowing for the natural oscillations of microphone membrane are considered. The technique for (tau) vt measurement is proposed on the strength that the signal form is determined by the oscillation mentioned above under low pressure (P vt of the vibrational state (nu) 1 + 3 (nu) 3 in H 2 O for the collisions H 2 O- H 2 O and H 2 O-air are presented.