Moazzen-Ahmadi, NasserWakwella, Praveen2021-09-282021-09-282021-09Wakwella, P. (2021). Spectroscopic investigation of isomers of the CO2-CO dimer in the 4.27 micron region (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/113978The following work reports the results obtained for the CO2-CO dimer in the ν_3 asymmetric CO2 stretching region (2350 cm^(-1) ). The clusters were formed in a supersonic jet expansion apparatus and probed using a tunable infrared radiation source provided by an OPO. The fundamental for both the C-bonded (isomer 1) and O-bonded (isomer 2) conformations for the dimer are observed for the natural isotopologue as well as for a 13CO2 and a 18O-13C-16O substituted form of the dimer. Combination bands involving the lowest frequency intermolecular mode (geared bending mode) are observed for both isomers. The spectra were fit with a semi-rigid asymmetric rotor Hamiltonian. The fundamentals were fit to b-type bands (〖ΔK〗_a=1,ΔK_c=1) and the combination bands were fit to a-type (ΔK_a=0) bands. In addition, two weak (ν_1,ν_2^(l_2 ),ν_3 )=(01^1 1)←(01^1 0) hot bands were observed for both isomers yielding very similar vibrational shifts as the ones observed for the fundamental. The vibrational shift in the fundamental was found to be Δν= +0.211 cm^(-1) for isomer 1 and Δν= +0.411 cm^(-1) for isomer 2. The intermolecular vibrational frequency was found to be 24.51 cm^(-1) for isomer 1 and 14.37 cm^(-1) for isomer 2 which are in good agreement with high level ab initio calculations (24.45 cm^(-1) and 14.68 cm^(-1)) and the frequencies observed in the CO stretch region (24.34 cm^(-1) and 14.19 cm^(-1) ). In addition, the vibrational shifts in the hot bands observed for both isomers are very similar to those observed for the fundamental. The shifts observed in this work are an order of magnitude smaller than the shifts observed in the CO stretch region which are +4.970 cm^(-1) and -2.982 cm^(-1) for isomer 1 and isomer 2, respectively. More theoretical work must be done to produce fully-coupled fully dimensional potential energy surfaces in order to provide precise predictions for vibrational shifts and accurately model the dimer. The interactions between van der Waals clusters play a key role in governing the dynamics of important physical phenomena (e.g., condensation, scattering, etc.). Therefore, studies of their spectra which provide precise unambiguous information about the nature of these interactions is central in describing important physical processes and developing new technologies.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Astronomy and AstrophysicsPhysics--MolecularOpticsPhysics--Radiationmaster thesis10.11575/PRISM/39290