Highly resolved infrared spectra of pure CO2ice (15-75 K)

Abstract

Context. The {$ν$}$_{2}$ bending mode of pure CO$_{2}$ ice around 15.2 {$μ$}m exhibits a fine double-peak structure that offers a sensitive probe to study the physical and chemical properties of solid CO$_{2}$ in space. Current laboratory spectra do not fully resolve the CO$_{2}$ ice features.

Aims: To improve the fitting of the observed CO$_{2}$ features, high-resolution solid-state infrared spectra of pure CO$_{2}$ ice are recorded in the laboratory for a series of astronomically relevant temperatures and at an unprecedented level of detail.

Methods: The infrared spectra of pure CO$_{2}$ ice were recorded in the 4000 to 400 cm$^{-1}$ (2.5-25 {$μ$}m) region at a resolution of 0.1 cm$^{-1}$ using Fourier transform infrared spectroscopy. Results: Accurate band positions and band widths (FWHM) of pure CO$_{2}$ ice are presented for temperatures of 15, 30, 45, 60, and 75 K. The focus of this spectroscopic work is on the CO$_{2}$ ({$ν$}$_{2}$) bending mode, but more accurate data are also reported for the $^{12}$CO$_{2}$ and $^{13}$CO$_{2}$ ({$ν$}$_{3}$) stretching mode, and CO$_{2}$ ({$ν$}$_{1}$+{$ν$}$_{3}$) and (2{$ν$}$_{2}$+{$ν$}$_{3}$) combination bands. FITS files of the spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/555/A85