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Collisional parameters of H2O lines: effect of temperature

Wagner, Georg und Birk, Manfred und Gamache, R.R. und Hartmann, J.-M. (2005) Collisional parameters of H2O lines: effect of temperature. Journal of Quantitative Spectroscopy and Radiative Transfer, 92, .

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Kurzfassung

High resolution Fourier transform spectra of H2O-air mixtures have been measured at 296, 742, and 980 K for total pressures of 0.5 and 1.0 atm in the region of the ƒÞ2 band. From these recordings, air-broadening coefficients have been determined for the doublet lines with Kc=J. From these data and previous experimental determinations, line-broadening parameters ƒ×(T) are obtained at all three temperatures for the doublet lines from J=0 up to J=16. These values are then used to deduce the temperature dependence exponent n, such that . The values of n obtained using the two elevated temperatures are consistent and show that line widths decrease with T for small J values (n „l +0.8), are almost temperature independent on T for J„l10, and increase with T for high J lines (n „l -0.3 for J„l15). This original result, which confirms theoretical predictions made about fifteen years ago with a semi-classical approach [J Chem Phys 1987;86:144-56], is analyzed here using an improved version of the model. Comparisons between measured and computed widths show that calculations cannot reproduce correctly the experimental results at all temperatures simultaneously. This failure is attributed to the use of an inappropriate interaction potential and to the very strong dependence of the broadening ƒ×(v) on the relative velocity v for high J lines. This strong variation of ƒ×(v) raises the question, which is discussed, of what calculated quantity is to be compared with measured values (i.e. , (T), or some other more complex mean to account for the velocity averaging of the spectral profile itself?). Nevertheless, when the temperature exponent n is considered, satisfactory agreement between experiments and predictions is obtained, particularly when the averaging of widths over the relative velocity distribution is made.

Dokumentart:Zeitschriftenbeitrag
Zusätzliche Informationen: LIDO-Berichtsjahr=2005,
Titel:Collisional parameters of H2O lines: effect of temperature
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Wagner, GeorgNICHT SPEZIFIZIERT
Birk, ManfredNICHT SPEZIFIZIERT
Gamache, R.R.NICHT SPEZIFIZIERT
Hartmann, J.-M.NICHT SPEZIFIZIERT
Datum:2005
Erschienen in:Journal of Quantitative Spectroscopy and Radiative Transfer
Referierte Publikation:Ja
In ISI Web of Science:Ja
Band:92
Seitenbereich:
Status:veröffentlicht
Stichwörter:water vapor, infrared, pressure broadening, high temperature
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EO - Erdbeobachtung
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EO - Erdbeobachtung
DLR - Teilgebiet (Projekt, Vorhaben):NICHT SPEZIFIZIERT
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Methodik der Fernerkundung
Hinterlegt von: Cornelia Roehl
Hinterlegt am:17 Feb 2006
Letzte Änderung:06 Jan 2010 22:41

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