Azzam, AAA; (2013) A linelist for the hydrogen sulphide molecule. Doctoral thesis , UCL (University College London).

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Abstract

The main aim of this study is to calculate a high temperature line list for H_2^32S. The results will form an important addition to the databases used for space applications, as well as laboratory investigations and pollution studies. The Dvr3d program suite is used to calculate the bound ro-vibrational energy levels, and dipole moment transition intensities. The most accurate available potential energy surface is empirically determined. This surface is used in our calculations after refining it by fitting to the up-to-date experimental data. For accurate line intensities, an accurate dipole moment surface (DMS) is needed. Constructing an accurate DMS for H_2S is well known to be difficult. A systematic ab initio study for the DMS has been performed. Different methods were tested in conjunctions with different basis sets taking into account the relativistic corrections and core-valence effects. The resulting (ATY2013) line list should be valid from 0 to 9000 cm^−1 and for temperature up to 2000 K. ATY2013 with cut off intensity of order 10^−31 cm^−1/(molecule×cm^−2) contains ∼36×10^6 transitions at 2000 K. In addition, the pure rotational transition frequencies of H_2S in natural abundance in its ground and first excited vibrational states have been recorded at room temperature at 0.005 cm^−1 resolution in the region 45 to 360 cm^−1 with a globar continuum source at SOLEIL synchrotron. 2400 rotational transitions are assigned to ground vibrational state of the four isotopologues H_2^32S, H_2^33S, H_2^34S and H_2^36S where 65% of them are new. 91 rotational transitions of H_2^36S were identified for the first time, as well as 406 rotational lines of H_2^32S and H_2^34S in their first excited bending vibrational state were recorded and analysed for the first time.

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