Photoacoustic measurements of the vibrational relaxation of the selectively excited ozone (nu(3)) molecule in pure ozone and its binary mixtures withO-2, N-2, and noble gases

The vibrational-translational relaxation time of the nu(3) state of ozone w as deduced from the phase shift of the photoacoustic detector signal relati ve to the amplitude-modulated radiation of the CO2 laser used for excitatio n of O-3. A special photoacoustic cell with a third electrode is used to el iminate an instrumentation phase shift caused by inertia of the microphone membrane. A three-level kinetic model of O-3 is presented and used to fit t he experimental and calculated phase shifts to determine the vibrational re laxation rate coefficients for pure O-3 and binary mixtures of O-3 with O-2 , N-2, and noble gases He, Ne, Ar, Kr, and Xe. These results are presented and compared with experimental data obtained for O-3, O-3-O-2, and O-3-N-2 by fluorescence and double resonance techniques. Experimental data for nu(3 ) state relaxation in binary mixtures with all noble atoms have been obtain ed for the first time. These new results are compared with the simplest mod el of interaction. Thus we obtain a very good agreement for the decrease of constants with the increase of the colliding partner mass. (C) 2000 Americ an Institute of Physics. [S0021-9606(00)00904-1].