Hot molecular line lists for extrasolar planets and industry

• Main Author: Barton, Emma Jane
• Other Authors: Tennyson, Jonathan ; Tinetti, Giovanna
• Published: University College London (University of London) 2016
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.746238

This research is a composite of projects which have individually contributed new results to their respective subjects, whilst collectively contributing to the updating of the ExoMol database to include pressure broadening. This research also represents a successful collaboration between academia and industry. A combination of empirical and ab initio methods were used to compute accurate ro-vibrational line lists for sodium chloride and potassium chloride and refine line lists for carbon monosulphide. Hot line lists for hydrogen chloride, formaldehyde, ammonia and methane were assessed by comparison to high resolution laboratory spectra at temperatures relevant to industrial spectral studies and extrasolar planets. Hot and room temperature Fourier transform infrared spectra of ammonia have been analysed using a variational line list available from ExoMol and, where available, experimental energy levels. Over 5000 new line assignments have been made, providing over 3000 new experimental energies in the range 500 - 11,000 wavenumbers. In addition, an analysis of a room temperature spectrum in the region 9000 - 10,400 wavenumbers has been started. A combined analysis of assigned high resolution experimental spectra of methane available from peer reviewed sources using the MARVEL algorithm has been started. It is intended that the resulting compilation of verified experimental ro-vibrational energies will aid the analysis of hot methane spectra in the region 1000 - 6300 wavenumbers. Custom built pressure and temperature dependent absorption cross sections for water, carbon monoxide, carbon dioxide and ammonia were generated using ExoMol and HITEMP line lists for new spectral retrieval code τ-REx, to facilitate the unbiased analysis of extrasolar planetary spectra. Finally, the data requirements and challenges related to data usage of these separate projects are used to inform the implementation of pressure broadening in the ExoMol database.