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Application of the Hartmann-Tran profile to analysis of H2O spectra



D Lisak, A. Cygan, D Bermejo, J L. Domenech, Joseph T. Hodges, Ha Tran


The Hartmann-Tran profile (HTP), which has been recently recommended as a new standard in spectroscopic databases, is used to analyze spectra of several lines of H$_2$O diluted in N$_2$, SF$_6$, and in pure H$_2$O. This profile accounts for various mechanisms affecting the line-shape and can be easily computed in terms of combinations of the complex Voigt profile. A multi-spectrum fitting procedure is implemented to simultaneously analyze spectra of H$_2$O transitions acquired at different pressures. Multi-spectrum fitting of the HTP to a theoretical model confirms that this profile provides an accurate description of H$_2$O line-shapes in terms of residuals and accuracy of fitted parameters. This profile and its limiting cases are also fit to measured spectra for three H$_2$O lines in different vibrational bands. The results show that it is possible to obtain accurate HTP line-shape parameters when measured spectra have a sufficiently high signal-to-noise ratio and span a broad range of collisional-to-Doppler line widths. Systematic errors in the line area and differences in retrieved line-shape parameters caused by the overly simplistic line-shape models are quantified. Also limitations of the quadratic speed-dependence model used in the HTP are demonstrated in the case of an SF$_6$ broadened H$_2$O line, which leads to a strongly asymmetric line-shape.
Physical Review A


isolated line shape, hard collision, quadratic speed dependence, velocity and internal state changes correlation, pCqSDHC profile, Hartmann-Tran profile


Lisak, D. , Cygan, A. , Bermejo, D. , Domenech, J. , Hodges, J. and Tran, H. (2015), Application of the Hartmann-Tran profile to analysis of H2O spectra, Physical Review A, [online],, (Accessed April 21, 2024)
Created June 8, 2015, Updated October 12, 2021