Temperature-dependent air broadening of water in the 1250-1750cm ~(-1) range

摘要

A Bruker IFS 120 HR Fourier-transform spectrometer has been used to investigate _(air) broadening of water vapor at a spectral resolution of 3×10 ~(-3)cm ~(-1) in the wavenumber range 1250-1750cm ~(-1). A new method for generating water vapor/air mixtures employing a 800l stainless steel mixing vessel and a steady flow through the absorption cell has been developed. A total of 46 measurements have been recorded, 33 (26 water+air, 7 pure water) of which have been used in the final analysis. The measurements covered the temperature range 205-315K, total _(air) pressure range 50-1000mb, water partial pressure range 0.001-5mb, absorption path range 16-8500cm and provided sufficient redundancy. Transmittance spectra corrected for various instrumental error sources were used in an automated single spectrum fit line parameter retrieval based on the Voigt profile. Average gas temperatures were fitted from retrieved water line strengths. From the retrieved Lorentzian line widths of each individual transition the _(air) and _(self)-broadening parameters and temperature exponents, γ _(air), γ _(self), n _(air), n _(self), or a subset thereof were fitted in an automated procedure. Various methods for validation of data product accuracy and data reduction model as well as comprehensive error analysis were applied. In total 593 γ _(air), 459 n _(air) and 469 γ _(self) values are reported, uncertainties for γ _(air) are given for reference temperatures 296 and 220K. Only data are reported where the γ _(air) uncertainty is <2 or the γ _(air),220K uncertainty is <5. The average uncertainties for γ _(air), γ _(air,220K), n _(air), and γ _(self) are 0.7, 2.2, 0.07, and 3, respectively. Comparisons with recent experimental work and HITRAN 2004 and HITRAN 2008 are presented.