Progress made towards context-free molecular structure determination from isotopologue rotational spectroscopy

Yeh, Lia

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https://hdl.handle.net/2142/107586 Copy

Description

Title

Progress made towards context-free molecular structure determination from isotopologue rotational spectroscopy

Author(s)

Yeh, Lia

Contributor(s)

• Patterson, David
• Yan, Jieyu
• Satterthwaite, Lincoln
• Finestone, Dylan

Issue Date

2020-06-24

Keyword(s)

Structure determination

Abstract

Recent algorithms\footnote{N.A. Seifert et. al., Journal of Molecular Spectroscopy 312, 13 (2015). }\footnote{L. Yeh, L. Satterthwaite, and D. Patterson, The Journal of Chemical Physics 150, 204122 (2019)} have demonstrated \textit{context-free} assignment of rotational constants---needing no knowledge of the chemical species other than the rotational spectrum. Efforts to date to subsequently determine molecular structure require further information including assignment of singly-substituted isotopologues\footnote{J. Yan and D. Patterson. Submitted to the 75th International Symposium on Molecular Spectroscopy (2020). }\footnote{K. Mayer et. al., Proceedings of the 74th International Symposium on Molecular Spectroscopy (2019).}, mass spectroscopy$^d$, and data mining$^d$\footnote{M. Muckle, A. Mikhonin, D. McDaniel, and/or J. Neill, Proceedings of the 74th International Symposium on Molecular Spectroscopy (2019).}. We investigate two methodologies to resolve sign ambiguities of Kraitchman’s substitution coordinates. The first methodology requires candidate rotational constants of doubly-substituted isotopologues. Given many such candidates, we have worked out how to determine 1) which candidates for singly- and doubly-substituted isotopologues are most probable, and 2) doubly-substituted atoms’ relative position octant. This is realizable given resolution of doubly-substituted species in natural abundance, which is 10-100x order of magnitude above our instrument's present signal to noise.\\ \indent The second methodology requires precision measurement of the electric dipole moments and magnetic g-factors of both the parent and singly-substituted isotopologues. The magnetic g-factor is measured via application of a large magnetic field to our microwave spectrometer, as done by Flygare et. al. (1969). For a 6 carbon molecule, this could be realized given the ability to resolve a $\approx 10^{-5}$ percent difference between magnetic g-factors of the parent and singly-substituted isotopolog species, as well as resolve the electric dipole moment to 4 or 5 significant figures. Improving the capabilities of microwave spectrometers to within these thresholds would therefore enable context-free molecular structure determination.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

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http://hdl.handle.net/2142/107586

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Copyright 2020 is held by the Author(s)

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