Here we present the first line-by-line measurements of interference parameters Y0k describing line-mixing effects in the weak overlapping regime for He-broadened CO lines in the 0–1 and 0–2 bands at 296 K. A detailed analysis of the line shape at intermediate perturber pressures (up to about 10 atm) has been performed, starting from previous theoretical calculations, which has demonstrated the possibility of an individual measurement of Yk parameters. The method is based on the existence of a component of the line shift, quadratic with the perturber pressure (density) and proportional to Y0k. Comparison of our measurements with results predicted from coupled-states calculations shows good overall agreement. Linear pressure shifts have also been simultaneously measured. The uncertainty on the data is important since linear shifts are very small; however, some features can be considered as significant although we have no clear understanding of them. Possible explanations are discussed.
We present laboratory measurements of the absorption cross sections of the ν5 band (540–580 cm−1) of chlorine nitrate made under stratospheric conditions of temperature and pressure. We use the measured cross sections and observed mid‐infrared stratospheric emission spectra to retrieve mid‐latitude vertical mixing ratio profiles for both day and night in the altitude range 20–34 km, and compare the results with a sunset profile obtained simultaneously from solar absorption measurements of the ν4 Q branch at 780 cm−1. The profiles obtained using these two methods are shown to be in excellent agreement, validating retrievals using the ν4 band. We also find good agreement in this altitude range between the observed day/night ratio and the results of a 1‐D photochemical model
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