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 Title: The 4.2 Micron Spectra Of Co2-co Dimer For Both The C- And O-bonded Isomers, Including Splitting Of The Degenerate ν2 Bend In The Presence Of Co Author(s): Wakwella, Praveen Contributor(s): Moazzen-Ahmadi, Nasser; McKellar, Bob; Barclay, A.J. Subject(s): Non-covalent interactions Abstract: CO$_2$-CO dimer was previously observed by high-resolution microwave and infrared spectroscopy in the form of a planar T-shaped C-bonded structure.\footnote{A.C. Legon, A.P. Suckley, \textit{Journal of Chemical Physics} \textbf{91} 4440 (1989).}$^,$\footnote{R.W. Randall, J.P.L. Summersgill, B.J. Howard, \textit{Journal Chemical Society Faraday Transactions} \textit{86} 1943 (1990).} More recently, spectra of a second isomer were observed in the stretching region of carbon monoxide.\footnote{S. Sheybani-Deloui, A.J. Barclay, K.H. Michaelian, A.R.W. McKellar, N. Moazzen-Ahmadi, \textit{Journal of Chemical Physics} \textbf{143} 121101 (2015).} This isomer has also a planar T-shaped structure, but with the CO flipped by $180^{\circ}$. Moreover, two intermolecular frequencies were measured for each isomer. These are in very good agreement with recent high level theoretical calculations.\\ Here, CO$_2$-CO dimer is observed in the carbon dioxide $\nu_3$ asymmetric stretch region ($\sim$2350 cm$^{-1}$). Both C-bonded and O-bonded isomers are analyzed for the normal isotopologue as well as for $^{13}$CO$_2$-CO and $^{16}$O$^{13}$C$^{18}$O-CO, the latter being the first observation of an asymmetrically substituted form for which all values of K$_a$ are allowed. Combination bands involving the lowest in-plane intermolecular mode are also observed yielding frequencies of 24.51 \wn for the C-bonded form and 14.37 \wn for the O-bonded form. In addition, two weak bands near 2337 \wn are assigned to CO$_2$ hot band transitions (01$^{1}$1) - (01$^{1}$0), yielding the splitting of the degenerate CO$_2$ bend into in-plane and out-of-plane components due to the presence of the CO. This splitting has rather different values for the C- and O- bonded isomers, 4.56 and 1.59 \wn, respectively, with the out-of-plane mode higher in energy than the in-plane for both cases. Issue Date: 2021-06-24 Publisher: International Symposium on Molecular Spectroscopy Genre: Conference Paper / Presentation Type: Text Language: English URI: http://hdl.handle.net/2142/111276 Date Available in IDEALS: 2021-09-24
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