Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5428083 | Journal of Quantitative Spectroscopy and Radiative Transfer | 2015 | 13 Pages |
â¢Temperature-dependent lineshape parameters and linestrengths were measured for 7 H2O transitions near 1.4 μm at 300 to 1300 K.â¢Voigt, Rautian, Galatry, and speed-dependent Voigt profile parameters were obtained for H2O and N2 perturbers.â¢Transitions with Jâ³=10-18 exhibited N2-broadening coefficients that increased with increasing temperature.â¢Collisional-narrowing and speed-dependent-broadening coefficients trended similarly with temperature and Jâ³.
Linestrengths and lineshapes for 7 H2O absorption transitions in the ν1+ν3 combination band near 1.4 μm were measured at high resolution using tunable diode laser absorption. H2O- and N2-perturbed lineshapes were measured at 300-1300 K and 2-760 Torr and Voigt, Galatry, Rautian, and quadratic-speed-dependent-Voigt profiles were least-squares fit to measured spectra using a multi-spectrum fitting routine. Transitions with Jâ³ of 6-18 were studied to highlight the importance of collisional resonance and illustrate how the best-fit lineshape parameters varied with Jâ³. The accuracy of the Voigt profile decreased as Jâ³ increased (especially for J=Kc doublets). For transitions in N2, the collisional-broadening temperature exponents varied from â0.8 to â0.4 (for the Voigt profile) as Jâ³ increased and this behavior coincided with increasing speed-dependent collisional-broadening coefficients. The quadratic-speed-dependent Voigt profile was found to offer the best combination of accuracy and robust lineshape parameters; however, Rautian and Galatry profiles provided similar performance.