EXPERIMENTAL STUDY OF TEMPERATURE-DEPENDENCE LAWS OF NON-VOIGT ABSORPTION LINE SHAPE PARAMETERS

Abstract

To improve the understanding of temperature-dependence laws of spectral line shape parameters, spectra of the $nu_3$ rovibrational band of CO$_2$ perturbed by 10, 30, 100, 300 and 1000~mbar of N$_2$ were measured at nine temperatures between 190~K and 330~K using a 22~cm long single-pass absorption cell in a Bruker IFS125~HR Fourier Transform spectrometer. The spectra were fitted employing a quadratic speed-dependent hard collision model in the Hartmann-Tran implementationfootnote{Ngo textit{et al.} JQSRT textbf{29}, 89-100 (2013); JQSRT textbf{134}, 105 (2014).}footnote{Tran textit{et al.} JQSRT textbf{129}, 199-203 (2013); JQSRT textbf{134}, 104 (2014).} extended to account for line mixing in the Rosenkranz approximation by means of a multispectrum fitting approach developed at DLRfootnote{Loos textit{et al.}, 2014; http://doi.org/10.5281/zenodo.11156.}. This enables high accuracy parameter retrievals to reproduce the spectra down to noise level and we will present the behavior of line widths, shifts, speed-dependence-, collisional narrowing- and line mixing-parameters over this 140~K temperature range.