Elucidation of the Ro-Vibrational Band Structures in the Silicon Tetrafluoride Spectra from Accurate Ab Initio Calculations

TL;DR

This paper creates detailed line lists for silicon tetrafluoride isotopologues using ab initio calculations, enabling better understanding of their ro-vibrational band structures.

Contribution

A new ab initio model generates accurate line lists for SiF4 isotopologues, revealing previously unknown ro-vibrational transitions.

Findings

Line lists cover 0–2500 cm−1 with 500 million transitions at 296 K.

Computed cold and hot band transitions were not previously available in literature.

Absorption cross-sections validated against experimental data from PNNL.

Abstract

We report the construction of comprehensive line lists for the three stable isotopologues of silicon tetrafluoride (28SiF4, 29SiF4, and 30SiF4) using a new effective Hamiltonian and dipole moment model built from accurate ab initio potential energy and dipole moment surfaces developed in this work. The vibrational energy levels were grouped into a series of polyads up to Pmax = 19, while the ro-vibrational energy levels were computed up to Jmax = 99. Each line list covers the spectral range 0–2500 cm−1 and contains almost 500 million transitions at T = 296 K, with each being generated from 685 vibrational states and sub-states. Most of the cold and hot band transitions computed in this work were not available in the literature beforehand. The absorption cross-sections computed from the produced line lists were successfully validated by direct comparison with the experimental data measured by Pacific Northwest National Laboratory at room temperature. Most of the ro-vibrational band structures observed in the experimental spectra can now be elucidated using the line lists proposed in this work.

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