Vibrational energy transfers in ozone excited into the (101) state from double-resonance measurements

Abstract

The vibrational energy transfer processes involved in the relaxation of O3 molecules from the excited states of the triad [(200)(101)(002)] have been investigated by double resonance (DR) measurements in O3–O2/N2 gas mixtures. It is shown that as long as the O3 molar fraction is higher than a few percent, the major processes are near-resonant V–V transfers occurring upon O3–O3 collisions. The rate coefficients of these processes have been determined. Also, from measurements performed with small O3 molar fractions, it has been possible to investigate the processes occurring upon O3–O2/N2 collisions. In this way, it is shown that the vibrational energy located in the stretching modes relaxes essentially through transfers to the ν2 mode. Finally, all the experimental DR signals have been simulated using a numerical model based on a kinetic scheme involving all the processes occurring in the relaxation, allowing us to deduce the corresponding rate coefficients.