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Title:Anomalous centrifugal distortion in HDO and spectroscopic data bases
Author(s):Coudert, L.H.
Subject(s):Atmospheric science
Abstract:The HDO molecule is important from the atmospheric point of view as it can be used to study the water cycle in the earth atmosphere.footnote{Herbin {em et al., Atmos. Chem. Phys.}~{bf 9} (2009) 9433; and Schneider and Hase, {em Atmos. Chem. Phys.}~{bf 11} (2011) 11207.} It is also interesting from the spectroscopic point of view as it displays an anomalous centrifugal distortion similar to that of the normal species H$_2$O. A model developed to treat the anomalous distortion in HDO should account for the fact that it lacks a two-fold axis of symmetry. A new treatment aimed at the calculation of the rovibrational energy of the HDO molecule and allowing for anomalous centrifugal distortion effects has been developed. It is based on an effective Hamiltonian in which the large amplitude bending $nu_2$ mode and the overall rotation of the molecule are treated simultaneously.footnote{Coudert, Wagner, Birk, Baranov, Lafferty, and Flaud, {em J. Molec. Spectrosc.}~{bf 251} (2008) 339.} Due to the lack of a two-fold axis of symmetry, this effective Hamiltonian contains terms arising from the non-diagonal component of the inertia tensor and from the Coriolis-coupling between the large amplitude bending $nu_2$ mode and the overall rotation of the molecule. This new treatment has been used to perform a line position analysis of a large body of infrared,footnote{Johns, {em J. Opt. Soc. Am. B}~{bf 2} (1985) 1340; Toth, {em J. Molec. Spectrosc.}~{bf 162} (1993) 20; Paso and Horneman, {em J. Opt. Soc. Am. B}~{bf 12} (1995) 1813; and Toth, {em J. Molec. Spectrosc.}~{bf 195} (1999) 73.} microwave,footnote{Messer, De Lucia, and Helminger, {em J. Molec. Spectrosc.}~{bf 105} (1984) 139; and Baskakov {em et al., Opt. Spectrosc.}~{bf 63} (1987) 1016.} and hot water vaporfootnote{Parekunnel {em et al., J. Molec. Spectrosc.}~{bf 210} (2001) 28; and Janca {em et al., J. Molec. Specrosc.}~{bf 219} (2003) 132.} data involving the ground and (010) states up to $J=22$. For these 4413 data, a unitless standard deviation of 1.1 was achieved. A line intensity analysis was also carried out and allowed us to reproduce the strength of 1316 transitions$^c$ with a unitless standard deviation of 1.1. In the talk, the new theoretical approach will be presented. The results of both analyses will be discussed and compared with those of a previous investigation.footnote{Tennyson {em et al., J. Quant. Spectrosc. Radiat. Transfer}~{bf 111} (2010) 2160.} The new spectroscopic data base built will be compared with HITRAN 2012.footnote{Rothman {em et al., J. Quant. Spectrosc. Radiat. Transfer}~{bf 130} (2013) 4.}
Issue Date:25-Jun-15
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:ACS
Genre:Conference Paper / Presentation
Date Available in IDEALS:2016-01-05

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