Measurements of Spectral Lineshape Parameters of Important Infrared-active Gases in Planetary Atmospheres at Relevant Temperatures

Abstract

Twenty-five years of experience with cooling spectroscopic samples to planetary atmospheric temperatures in the laboratory, the acquisition of a state-of-the-art Fourier-transform spectrometer, and an accurate non-linear least-squares line-fitting routine have enabled us to obtain infrared line intensities, collision-broadened linewidths, lineshifts, and some aspects of the collision-broadened lineshape with unprecedented accuracy. We present in this paper some of the results obtained in our laboratory in the fundamental bands of CO, CO2, N2O, CH4, CH3D, C2H2, and NH3 at temperatures and other conditions relevant to various planetary atmospheres. A critical comparison with other published work, including some well-known spectroscopic databases, and some revealing trends as to the variation of the spectral line parameters with temperature are presented.