Knowledge Bank

The $\nu 1\leftrightarrow \nu 3$ Coriolis-assisted intermode transfers in $O3-M$ gas mixtures $(M=O2$ and $N2$) have been investigated in the temperature range $200-300K$ by means of a time-resolved double resonance technique using two $CO2$ lasers. The rate coefficients $k1-3O3$ and $k1-3H$ for the processes involving $O3-O3$ and $O3-M$ collisions respectively have been deduced from the rate constants measured as a function of the molar fraction of $O3$ in the gas mixtures. The high values obtained for the rate coefficients $(105-105s-1Torr-1)$ are due to the Coriolis interaction which leads to an important enhancement of the efficiency of intermode transfer, even for collisions with non-dipolar partners. The temperature dependences of the rate coefficients were found to be well fitted, in the investigated temperature range, by a function of the form $k1-3(T)=k1-3(300)\times (300T)n$. Near-resonant vibrational energy transfers populating higher states have also been investigated. Calculations based on the Sharma-Brau theory using first-order Born approximation, a dipole-dipole interaction potential and equivalent straight trajectories of Robert and Bonamy were performed. The calculated rate coefficients are found in good agreement with the experimental ones within whole range of temperature.