Line parameters of the 782 nm band of CO2

Abstract

The 782 nm band of CO2, in a transparent window of Earth's atmosphere, was the first CO2 band observed 80 yr ago in the spectra of Venus. The band is very weak and therefore not saturated by the thick atmosphere of Venus, but its spectral parameters are still very limited due to the difficulty of detecting it in the laboratory. It is the highest overtone (ν1 + 5ν3) of CO2 given in widely used spectroscopy databases such as HITRAN and GEISA. In the present work, the band is studied using a cavity ring-down spectrometer with ultra-high sensitivity as well as high precision. The positions of 55 lines in the band were determined with an absolute accuracy of 3 × 10-5 cm-1, two orders of magnitude better than previous studies. The line intensities, self-induced pressure broadening coefficients, and the shift coefficients were also derived from the recorded spectra. The obtained spectral parameters can be applied to model the spectra of the CO2-rich atmospheres of planets like Venus and Mars. © 2013. The American Astronomical Society. All rights reserved.