Spectroscopic Characterization of Hydrogen Bonded and Halogen Bonded Interactions
Abstract
Prototypical hydrogen-bonded and halogen-bonded systems give unique insight into the characteristics of weakly interacting systems. Spectroscopic analysis of fundamental, combination, and hot bands of these types of systems has yielded structural properties, molecular dynamics and other molecular parameters. The experimental results from the gas-phase spectroscopy were compared with the results of compound-model morphed potentials.
Experimental spectroscopic analysis was accomplished through the application of a near infrared quantum cascade laser (QCL) based spectrometer to a continuous wave supersonic slit jet expansion with several different combinations of CO and HX (X= F, Cl, Br, I, CN, CCH) species. Spectroscopic analysis of fundamental, combination and hot bands of the CO stretching vibrations provided rovibrational parameters for low frequency intermolecular vibrations. Investigation into the blue frequency shifts in the complexes of the C-O vibrations permitted comparison of the strength and of the resulting effects of the hydrogen and halogen bonding within the systems.
Structural properties and other molecular parameters of OC-HCN were compared with corresponding properties predicted using morphed potentials for the homologous series OC-HX (X = F, Cl, Br, I). Analysis of ν2, ν2 +ν 7^1−ν 7^1, ν2 +ν 7^1, and ν2 +ν6^1 vibrations in OC-HCN enabled the generation of a 5-dimensional semi-empirical intermolecular potential. A five-dimensional compound-model morphed potential was also generated for the halogen-bonded intermolecular interaction OC-BrCl, which could then be compared with the alternatively hydrogen-bonded dimers OC-HX (X = F, Cl, Br) giving further insight into the nature of these types of interactions.
A new spectrometer was designed to enable the study of DI. The ν1 spectra of OCDI and OC-ID, as well as ν2 of OC-DI and OC-ID have been recorded using a quantum cascade laser pulsed slit supersonic jet spectrometer with an astigmatic multipass cell. The results confirmed the prediction of ground state deuterium isotopic isomerization, originally proposed by using a generated morphed potential.
Finally, another new quantum cascade laser spectrometer was designed to utilize a continuous wave supersonic slit jet expansion with an astigmatic multipass cell. The spectrum of Ar-NO was recorded over the region 1856.8-1887.4 cm^-1 followed by the recording of the NO-H2O spectra in this region, both of which had never before been recorded in these regions and are open-shell systems.
Subject
weakly bound complexesrovibrational spectroscopy
quantum cascade laser spectrometer
infrared spectroscopy
potential energy surfaces
Citation
Scott Jr., Kevin Wayne (2016). Spectroscopic Characterization of Hydrogen Bonded and Halogen Bonded Interactions. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /158048.