Knowledge Bank

We have evaluated collision broadened halfwidths of ozone with nitrogen and oxygen as the perturbing gases. Calculations using conventional Anderson $theory1$ or quantum Fourier transform $theory2$ are shown to be some 25 to 35% too low when compared to the experimental $measurements3,4$. We show that it is important to consider more realistic collision dynamics in the calculations. By replacing the classical path trajectories by non-linear trajectories with constant velocities chosen to give the equations of motion exact to first order in time we develop the interruption function in terms of the actual distance of closest approach determined by the intermolecular potential. This improvement to the theory results in $N2$- and $O2$- broadened halfwidths which are in good agreement with the experimental measurements. Air-broadened halfwidths have been evaluated from the nitrogen and oxygen results via the formula $\gamma air=0.79\gamma N2+0.21\gamma 02.$ The results agree with the air-broadened $measurements3$ to better than 5%.