Applying Intensity-based Methods to Disentangle Microwave Spectra of Complex Mixtures: Analysis of Weakly Bound Clusters of 1,1-Difluoroethylene/CO2

Author

Hannah Fino, Eastern Illinois UniversityFollow

Graduate Program

Chemistry

Degree Name

Master of Science (MS)

Semester of Degree Completion

Spring 2022

Thesis Director

Rebecca A. Peebles

Thesis Committee Member

Radu F. Semeniuc

Thesis Committee Member

Edward M. Treadwell

Thesis Committee Member

Zhiqing Yan

Abstract

Microwave spectroscopy is used to study the solvent-solute interactions between molecules of CO₂ and fluoroethylenes by analyzing the formation of weakly-bound clusters in a gaseous mixture. One of the challenges to analyzing microwave spectra obtained for these weakly-bound species is that spectra for individual clusters are mixed together in an original complex spectrum. This prompts development of automated techniques that could separate complex data into subsets of related data to be more easily analyzed.

The techniques developed in this work are founded on intensity-based analyses, following the work of Dr. Robert Field on Extended Cross Correlation (XCC). The XCC method was based on the notion that intensities of the same transitions in two different spectra recorded with one varying experimental parameter could be used to generate an intensity vs. intensity plot that reveals patterns of related data along linear rays. In the present study, two methods were developed to identify transitions belonging to the rays that were observable in the intensity vs. intensity plot. Those techniques were the Ratio Method (based on the ratio between two intensities for the same transition) and the Density of Points Method (based on the number of transitions that lie on a particular ray).

The Density of Points Method was able to extract seven spectra from an analysis on 1,1-difluoroethylene (DFE)/CO₂ spectra. Two DFE/CO₂ clusters, (DFE)₁(CO₂)₂ and (DFE)₁(CO₂)₃, could be correlated to assignments made using Ratio Method spectra and aided in identifying a new DFE/CO₂ cluster, (DFE)₁(CO₂)₄, using a Density of Points Method unknown spectrum.

Recommended Citation

Fino, Hannah, "Applying Intensity-based Methods to Disentangle Microwave Spectra of Complex Mixtures: Analysis of Weakly Bound Clusters of 1,1-Difluoroethylene/CO2" (2022). Masters Theses. 4948.
https://thekeep.eiu.edu/theses/4948