Infrared Spectra Of (co₂)_n - (rare Gas)_m Trimers And Tetramer, (n,m) = (1,2), (1,3), (2,1)

McKellar, A.R.W.

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https://hdl.handle.net/2142/111262 Copy

Description

Title

Infrared Spectra Of (co₂)_n - (rare Gas)_m Trimers And Tetramer, (n,m) = (1,2), (1,3), (2,1)

Author(s)

McKellar, A.R.W.

Contributor(s)

• Moazzen-Ahmadi, Nasser
• Pietropolli Charmet, Andrea
• Barclay, A.J.

Issue Date

2021-06-25

Keyword(s)

Clusters/Complexes

Abstract

"\textbf{(\textit{n},\textit{m}) = (1,2).}~~ CO$_2$-Ar$_2$ has previously been studied in the microwave\footnote{Y. Xu, W. J\""{a}ger, and M.C.L. Gerry, \textit{J. Mol. Spectrosc.} \textbf{157}, 132 (1993).} and infrared.\footnote{J.M. Sperhac, M.J. Weida, and D.J. Nesbitt, \textit{J. Chem. Phys.} \textbf{104} 2202 (1996).} Its structure has two Ar atoms occupying equivalent positions around the 'equator' of the CO$_2$, giving $C_{2v}$ symmetry. Here we report observation of analogous infrared spectra of CO$_2$-Ne$_2$ and CO$_2$-Xe$_2$. Meanwhile, for CO$_2$-Ar$_2$ we observe a new $a$-type combination band giving an intermolecular bending frequency of 32.2 \wn. Unlike the fundamental band, the combination band is free of interference from stronger CO$_2$-Ar transitions. Also, we observe CO$_2$-Ar$_2$ in the CO$_2$ (01$^{1}$1) - (01$^{1}$0) hot band region, as well as weak fundamental band spectra of the mixed trimers CO$_2$-Rg-He, with Rg = Ne, Ar, Xe. \textbf{(\textit{n},\textit{m}) = (1,3).}~~ An interesting band near 2345.2 \wn~is assigned to CO$_2$-Xe$_3$, whose structure appears to have $C_s$ symmetry containing a xenon trimer (near equilateral triangle) and a CO$_2$ positioned so that two of the Xe atoms are in equivalent near equatorial positions. \textbf{(\textit{n},\textit{m}) = (2,1).}~~ We have assigned spectra of new trimers, (CO$_2$)$_2$-Rg. The Xe-containing species was noticed first, and this led us to identify weaker spectra with Ar and (even weaker) Ne. Their structures resemble having a CO$_2$ dimer (planar slipped parallel) with the Rg atom located 'above' the dimer plane on (or close to) the dimer symmetry axis, analogous to (CO$_2$)$_2$-CO.\footnote{A.J. Barclay, A.R.W. McKellar, and N. Moazzen-Ahmadi, \textit{Chem. Phys. Lett.} \textbf{677}, 127 (2017).} In the future, it should be possible to assign the various Kr clusters and to optimize each cluster by varying the expansion gas mixtures."

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111262

DOI

10.15278/isms.2021.FI01

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