Abstract

We report measurements of the self-broadening coefficients of the 4978-cm^-1 vibrational band of CO₂ as well as rovibrational line intensity parameters at a high resolution of 0.004 cm^-1 by using a Bomem Fourier transform spectrometer. From these measurements, performed at several different temperatures ranging from 165 to 300 K, we have derived the temperature dependence of the linewidths. This is to provide laboratory data relevant to conditions expected by planetary and atmospheric scientists and probably to contribute to a better theoretical understanding of the temperature dependence. The line-shape parameters of interest are determined by comparing experimentally obtained and computed spectra, which comprise a nonlinear point-by-point least-squares determination of the line-center frequency, intensity, and broadening coefficient, wherein the line is modeled by the Voigt profile convolved with an instrument function. For the temperature dependence of the broadening coefficients we have found n = 0.75, where this is the exponent appropriate to the (usual) power law expression. This quantity is almost the same for different J values, except for the lower ones, where, however, we need to devote a more in-depth look at our results. For the band intensity we obtained S_band = 0.9515 cm⁻¹/cm · atm at STP, and for the rotationless transition moment squared R² = 0.1812 × 10^-4 D.

© 1988 Optical Society of America