A Computed Room Temperature Line List for Phosphine

TL;DR

This paper presents a detailed, computed line list for phosphine at room temperature, covering a broad spectral range with high accuracy, useful for atmospheric and astrophysical applications.

Contribution

It introduces a new refined potential energy surface and computes an extensive line list for phosphine, improving spectral data accuracy and coverage for temperatures up to 300 K.

Findings

Line list contains 137 million transitions

Good agreement with experimental spectra, especially rotational spectrum

Provides data suitable for atmospheric and astrophysical modeling

Abstract

An accurate and comprehensive room temperature rotation-vibration transition line list for phosphine (31PH3) is computed using a newly refined potential energy surface and a previously constructed ab initio electric dipole moment surface. Energy levels, Einstein A coefficients and transition intensities are computed using these surfaces and a variational approach to the nuclear motion problem as implemented in the program TROVE. A ro-vibrational spectrum is computed, covering the wavenumber range 0 to 8000 cm-1. The resulting line list, which is appropriate for temperatures up to 300 K, consists of a total of 137 million transitions between 5.6 million energy levels. Several of the band centres are shifted to better match experimental transition frequencies. The line list is compared to the most recent HITRAN database and other laboratorial sources. Transition wavelengths and intensities are generally found to be in good agreement with the existing experimental data, with particularly close agreement for the rotational spectrum. An analysis of the comparison between the theoretical data created and the existing experimental data is performed, and suggestions for future improvements and assignments to the HITRAN database are made.