Knowledge Bank

We have calculated nitrogen-broadened halfwidths of ozone over a temperature range from 200 to 350 K. The calculations were done using the QFT-ID $method1$ which has been shown to give halfwidths to better than 10%. The temperature dependence of the broadening coefficient has been evaluated for a wide range of transitions that cover J from 1 to 35, the full manifold of Ka for particular J values and for some transitions of stratospheric importance. The temperature dependence is given in terms of the temperature exponent, n, from the expression $\gamma (T)/\gamma (T0)=(T0/T)n$, for the 126 transitions studied. The results indicate an average temperature exponent of n = 0.77 for $N2$-broadening of ozone. The results are not strongly dependent on the rotational quantum number J but do show some dependence on Ka. Comparison is made with experimentally determined temperature $coefficients2,3$ and other theoretical $calculations.4,5$