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Weakly-bound clusters of atmospheric molecules: infrared spectra and structural calculations of (CO2)n-(CO)m-(N2)p, (n,m,p) = (2,1,0), (2,0,1), (1,2,0), (1,0,2), (1,1,1), (1,3,0), (1,0,3), (1,2,1), (1,1,2)

Authors :
Barclay, A. J.
McKellar, A. R. W.
Charmet, A. Pietropolli
Moazzen-Ahmadi, N.
Publication Year :
2022

Abstract

Structural calculations and high-resolution infrared spectra are reported for trimers and tetramers containing CO$_2$ together with CO and/or N$_2$. Among the 9 clusters studied here, only (CO$_2$)$_2$-CO was previously observed by high-resolution spectroscopy. The spectra, which occur in the region of the $\nu_3$ fundamental of CO$_2$ (~2350 cm$^{-1}$), were recorded using a tunable optical parametric oscillator source to probe a pulsed supersonic slit jet expansion. The trimers (CO$_2$)$_2$-CO and (CO$_2$)$_2$-N$_2$ have structures in which the CO or N$_2$ is aligned along the symmetry axis of a staggered side-by-side CO$_2$ dimer unit. The observation of two fundamental bands for (CO$_2$)$_2$-CO and (CO$_2$)$_2$-N$_2$ shows that this CO$_2$ dimer unit is non-planar, unlike (CO$_2$)$_2$ itself. For the trimers CO$_2$-(CO)$_2$ and CO$_2$-(N$_2$)$_2$, the CO or N$_2$ monomers occupy equivalent positions in the 'equatorial plane' of the CO$_2$, pointing toward its C atom. To form the tetramers CO$_2$-(CO)$_3$ and CO$_2$-(N$_2$)$_3$, a third CO or N$_2$ monomer is then added off to the 'side' of the first two. In the mixed tetramers CO$_2$-(CO)$_2$-N$_2$ and CO$_2$-CO-(N$_2$)$_2$, this 'side' position is taken by N2 and not CO. In addition to the fundamental bands, combination bands are also observed for (CO$_2$)$_2$-CO, CO$_2$-(CO)$_2$, and CO$_2$-(N$_2$)$_2$, yielding some information about their low-frequency intermolecular vibrations.<br />Comment: 35 pages, 7 figures and 4 tables

Details

Language :
English
Database :
OpenAIRE
Accession number :
edsair.doi.dedup.....15403680a9510c3d60ddf8ec392f4f89