Infrared spectra of (CO2)2 - Rg trimers, Rg = Ne, Ar, Kr, and Xe

High resolution spectra of (CO2)(2)-Rg trimers (Rg = Ne, Ar, Kr, and Xe) in the region of the CO2 v(3) fundamental (approximate to 2350 cm(-1)) are reported, using a tunable OPO laser source to probe a pulsed supersonic slit jet expansion. These (CO2)(2)-Rg transitions tend to be hidden among stronger spectra due to other species, such as CO2-Rg and (CO2)(2). Each trimer consists of a (CO2)(2) unit which is similar to the free carbon dioxide dimer (planar parallel staggered) plus an Rg atom located out-of-plane on the dimer C-2 symmetry axis, but the (CO2)(2) unit may not remain exactly planar in the dimer. Experimental structures show that the C-Rg bond lengths in the trimers are similar to those in the corresponding CO2-Rg dimers. As well, the vibrational band origin shifts, relative to (CO2)(2) itself, are similar to those of CO2-Rg relative to CO2.

Automated summary

High resolution spectra of (CO2)(2)-Rg trimers (Rg = Ne, Ar, Kr, and Xe) in the region of the CO2 v(3) fundamental are reported. Experimental structures show that the trimers have similar structures to CO2-Rg dimers and exhibit similar vibrational band shifts.