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The continuum absorption in H2O+N2 mixture in the 3 - 5 ¿m spectral region at temperatures from 326 to 363 K



Yuri I. Baranov


The absorption spectra of H2O+N2 mixtures, as well, as the spectra of pure gases, have been measured using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm-1. The sample temperatures were 325, 339, 353, and 364 K. Water vapor pressures varied from 8 kPa (60 torr) to 34.5 kPa (259 torr). The nitrogen pressure was kept constant at about 414 kPa (4.1 atm). The path length was 100 m. The continuum absorption coefficients obtained in the region 3.1-5 μm do not depend significantly on temperature, as is predicted by the well known MT_CKD model. But there are significant deviations in absorption spectral behavior and magnitude. In the region around 5 μm the measured absorption coefficients Cf are about two times larger than those of the model. This deviation rapidly growths at shorter wave lengths, reaching the maximum of two orders of magnitude in the middle of the window at 4 μm. At this point, the deviation starts to decrease significantly and around 3.2 μm our results are in agreement with the MT_CKD model. This behavior of the deviation is due to the broad and structureless feature in the region of the nitrogen fundamental band. Most likely, this feature is the N2 fundamental band induced by collisions between H2O and N2 molecules. The data obtained and a comparison with the results from the other available sources are presented.
Journal of Quantitative Spectroscopy and Radiative Transfer


continuum absorption, H2O - N2 mixtures, 3 - 5 ¿m spectral region, 326 to 363 K temperature


Baranov, Y. (2013), The continuum absorption in H2O+N2 mixture in the 3 - 5 ¿m spectral region at temperatures from 326 to 363 K, Journal of Quantitative Spectroscopy and Radiative Transfer, [online], (Accessed April 14, 2024)
Created June 13, 2013, Updated November 10, 2018