High resolution infrared spectroscopy of carbon dioxide clusters up to (CO 2 ) 13

• Published in: The Journal of chemical physics 2011-07, Vol.135 (4), p.044315-044315-11
• Main Authors: Norooz Oliaee, J., Dehghany, M., McKellar, A. R. W., Moazzen-Ahmadi, N.
• Format: Article
• Language: English
• Subjects: Gas Phase Dynamics and Structure: Spectroscopy, Molecular Interactions, Scattering, and Photochemistry
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.3615543

Thirteen specific infrared bands in the 2350 cm −1 region are assigned to carbon dioxide clusters, (CO 2 ) N , with N = 6, 7, 9, 10, 11, 12 and 13. The spectra are observed in direct absorption using a tuneable infrared laser to probe a pulsed supersonic jet expansion of a dilute mixture of CO 2 in He carrier gas. Assignments are aided by cluster structure calculations made using two reliable CO 2 intermolecular potential functions. For (CO 2 ) 6 , two highly symmetric isomers are observed, one with S 6 symmetry (probably the more stable form), and the other with S 4 symmetry. (CO 2 ) 13 is also symmetric ( S 6 ), but the remaining clusters are asymmetric tops with no symmetry elements. The observed rotational constants tend to be slightly (≈2%) smaller than those from the predicted structures. The bands have increasing vibrational blueshifts with increasing cluster size, similar to those predicted by the resonant dipole-dipole interaction model but significantly larger in magnitude.