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Theoretical work on the water monomer and dimer

Theoretical work on the water monomer and dimer. Matt Barber Jonathan Tennyson University College London matt@theory.phys.ucl.ac.uk December 2008. Outline of work so far. Improvements to water line list Extended to cover 800-19,600 cm -1 New sources added

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Theoretical work on the water monomer and dimer

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  1. Theoretical work on thewater monomer and dimer Matt Barber Jonathan Tennyson University College London matt@theory.phys.ucl.ac.uk December 2008

  2. Outline of work so far • Improvements to water line list • Extended to cover 800-19,600 cm-1 • New sources added • Partition function for water dimer • Few energy levels filled at low temperatures • Most dimers are in the ground vibrational state • Rotational levels convergent up to 20K • No useful published comparisons

  3. Line lists for 11000-19500 cm-1 • HITRAN • Good reference for strong lines • BT2 • R J Barber and Jonathan Tennyson, UCL • Theoretical model with experimentally determined energy levels. • Retrofitted experimental spectra • Tolchenov R, Tennyson J: "Water line parameters from refitted spectra constrained by empiricalupper state levels: study of the 9500-14500 cm-1 region". JQSRT, 109(4), 559-568 (2008). • Grenoble data • Very accurate measurements using cavity ring down spectroscopy • Comparatively clean area for HITRAN lines

  4. Line lists for 750-7500 cm-1 Coudert The H216O molecule: Line position and line intensity analyses up to the second triad, L.H. Coudert, G. Wagner, M. Birk, Yu.I. Baranov, W.J. Lafferty, J.-M. Flaud, JMS (preprint 2008) Brussels-Reims Fourier transform measurements of water vapor line parameters in the 4200-6600 cm-1 region, Jenouvrier, A; Daumont, L; Regalia-Jarlot, L, et al., JQSRT (105/2. pp 326-355, 2007) Giessen Water vapor absorption line intensities in the 1900-6600 cm-1 region, Mikhailenko, SN; Albert, KAK; Mellau, G, et al., JQSRT  (109/16, pp2687-2696, 2008) Grenoble Weak water absorption lines around 1.455 and 1.66 mu m by CW-CRDS, Mikhailenko, SN; Le, W; Kassi, S, et al., JMS (244/2, pp170-178, 2007)

  5. Dimer partition function at 20K • Only lowest vibrational state occupied • Rotational states up to J=20 occupied • Statistical weights g from Groenemboom et al. • G16 Symmetry • Equation:

  6. Conclusion • Monomer linelist • Now covering from • Submit to BADC? • Publish? • Dimer partition function • Convergent at 20K • Reasonable at 50K • Need many more levels for room temperature • No low temperature comparisons available

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