Temperature, pressure, and perturber dependencies of line-mixing effects in CO2 infrared spectra. I. Σ←Π Q branches

Publisher Website
Google Scholar
Abstract
Experimental and theoretical results on the influence of line mixing on the shape of infrared CO 2 Q branches of importance for atmospheric applications are presented. Two Q branches of Σ←Π symmetry, which lie near 618 and 720 cm −1 and belong to the 10 0 0 II ←01 1 0 I and 10 0 0 I ←01 1 0 I bands, have been studied for many conditions of temperature (200–300 K), total pressure (0.5–10 atm), and mixture (with He, Ar, O 2 , and N 2 ). The theoretical approach used is based on the Energy Corrected Sudden approximation; its parameters have been deduced from both line-broadening data and measured absorption by the Q branches. Comparisons between experimental and computed spectra demonstrate the quality of the model, regardless of the conditions. Detailed analysis of the influences of the Q-lines spectral spacing, temperature, total pressure, and collision partner are presented. They show that significantly larger line-mixing effects are obtained when CO 2 –He is considered with respect to CO 2 –(Ar,O 2 ,N 2 ) . This is analyzed in terms of the relative contributions of the short- and midrange interaction forces and of propensity rules resulting from the coupling of angular momenta.

This publication has 37 references indexed in Scilit: