Analytical Evaluation of the Maxwell-Boltzmann Velocity Average in Pressure-Broadened Half-Width Calculations.
For the first time the half-width within the complex Robert-Bonamy (CRB) formalism is calculated without making the mean relative thermal velocity approximation. The application is to the nitrogen-broadened half-width of the 500.4-GHz transition (34(2 32)<--34(1 33)) of the ground vibrational state of ozone. For each state of the perturber, the optical cross sections are determined at a number of velocities with the intermolecular potential taken as a sum of electrostatic contributions and Lennard-Jones (6-12) atom-atom components. The dynamics of the collision process are correct to second order in time. Using a nonlinear least-squares fitting method, the optical cross sections are fit to a double power law, which allows the velocity integral for the half-width to be done analytically. The results are compared with the mean relative thermal velocity complex Robert-Bonamy calculations and with measurement. The temperature dependence of the half-width, which is necessary for reduction of remotely sensed data, is determined from both methods and compared with experiment. Copyright 2001 Academic Press.
Gamache
Robert R.
RR
Department of Environmental, Earth, and Atmospheric Sciences, University of Massachusetts Lowell, 1 University Avenue, Lowell, Massachusetts, 01854