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

10 págs.; 9 figs.; 1 tab.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 H2O diluted in N2, SF6, and in pure H2O. 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 H2O transitions acquired at different pressures. Multi-spectrum fitting of the HTP to a theoretical model confirms that this profile provides an accurate description of H2O 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 H2O 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 SF6 broadened H2O line, which leads to a strongly asymmetric line-shape. & 2015 Elsevier Ltd. All rights reserved.The research is part of the program of the National Laboratory FAMO in Toruń, Poland, and is supported by the Polish National Science Centre Projects nos. DEC-2011/01/B/ST2/00491 and DEC-2013/11/D/ST2/ 02663. The research is also supported by the Foundation for Polish Science TEAM Project co-financed by the EU European Regional Development Fund. A. Cygan is partially supported by the Foundation for Polish Science START Project. Dr. Hodges is supported by the Greenhouse Gas and Climate Sciences Measurement Program of the National Institute of Standards and Technology. Drs. Bermejo and Domenech have been supported by Grants CSD2009-00038 (Consolider Astromol) and FIS2012- 38175 from the Spanish Ministry of Economy and Competitiveness.Peer Reviewe