ANALYSIS OF EXPERIMENTAL SPECTRA OF PHOSPHINE IN THE TETRADECAD NEAR 2.2 μM USING AB INITIO CALCULATIONS

Sung, Keeyoon

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https://hdl.handle.net/2142/122662 Copy

Description

Title

ANALYSIS OF EXPERIMENTAL SPECTRA OF PHOSPHINE IN THE TETRADECAD NEAR 2.2 μM USING AB INITIO CALCULATIONS

Author(s)

Sung, Keeyoon

Contributor(s)

• Tyuterev, Vladimir
• Rey, Michael
• Campargue, Alain
• Nikitin, Andrei V.

Issue Date

2023-06-22

Keyword(s)

Mini-symposium: Infrared Spectroscopy in the JWST Era

Abstract

In support of planetary atmosphere remote sensing and exobiology, we studied spectroscopy of phosphine (PH₃) in the full Tetradecad range, involving 26 rotationally resolved bands, for the first time. For this, we analyzed high-resolution FT-IR spectra in the 3769 - 4763 cm−¹ region recorded at temperatures 200 K and 296 K. Overall 3242 line positions were assigned and modeled by using a combined theoretical model based on ab initio calculations. The total nuclear motion Hamiltonian, including ab initio Potential Energy Surface (PES), was reduced to an effective Hamiltonian using the high- order contact transformation method adapted to vibrational polyads of the AB₃ symmetric top molecules, followed by empirical optimization of the parameters. At this step, the measured line positions could be reproduced with a standard deviation of 0.0026 cm−¹, providing unambiguous identification for the observed features. We also obtained the effective dipole transition moments of the bands by fitting to the intensities from variational calculations using the ab initio Dipole Moment Surface (DMS). The assigned lines were used to additionally determine 1609 vibration-rotational levels up to Jmax = 18 with their energy in the range of 3896-6037 cm−¹. Transitions for all 26 sublevels of the Tetradecad were identified but with noticeably a fewer number of transitions for fourfold excited bands due to their weaker intensity. We present the latest results and comparison with existing experimental spectra in the discussion of their validation and applications toward planetary atmosphere characterization.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122662

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