Knowledge Bank

We report the first measurements of the temperature dependence of the nitrogen broadening coefficients of selected ozone rovibrational transitions. We recorded spectra of the $v3$ band at approximately 1000 $cm-1$ with a Bomem Fourier transform spectrometer at a resolution of $0.004cm-1$ and broadened by nitrogen at pressures ranging from 0 to 80 torr. The temperature was varied over the range of 180 K to 296 K in 20 K increments from one set of broadend spectra to the next. The pressure broadening coefficient, $\gamma$(T), for a particular transition at a temperature, T, was obtained as the slope of a straight line plot of the collision broadened half-width vs. added nitrogen pressure. The dependence of the pressure broadening coefficient was assumed to be given by the power law, $\gamma (T)/\gamma (T0)=(T/T0)-n,$ where $T0$ is a reference temperature (296 K) and n is the temperature exponent. A plot of In $(\gamma (T))$ vs. In(296 K/T) therefore yields n. Values of n have been obtained for approximately 30 transitions in the $v3$ band and are close to the theoretically predicted average value of 0.76. We compare our experimentally determined temperature coefficients to those predicted by Quantum Fourier Transform $theory1$.