Chirped-pulse Fourier-transform microwave spectroscopy (CP-FTMW) is a technique with potentially broad analytical applications due to the unique, fingerprint-like nature of a rotational spectrum. Although for a given substance, a relatively small number of rotational transitions fall within the frequency range of a single CP-FTMW scan, a complex sample mixture often leads to incredibly dense spectra and it is necessary to deconvolute these to identify groups of lines from different species before patterns can be recognized. We have recently utilized several approaches based on characterizing the concentration dependence of transitions of different species within a mixture. Initial studies of vinyl fluoride (VF)/CO2 clusters in a series of variable concentration scans were very successful, leading to a total of 10 new species assigned, corresponding to VF/CO2 clusters ranging from trimers up to pentamers. To test the broader applicability of these methods, the same analytical approaches are now being applied to 1,1-difluoroethylene (DFE)/CO2 mixtures. One weakly bound complex, likely corresponding to a tetramer, has so far been identified. For both the VF and DFE clusters, the ABCluster program has been applied, along with density functional theory calculations, to assist in determining likely structural arrangements corresponding to observed spectra. We are now developing a picture of how the arrangement of CO2 molecules around fluoroalkenes varies as the numbers of fluoroethylene and CO2 molecules increase.

New approaches to analysis of complex mixtures using chirped-pulse Fourier-transform microwave spectroscopy: Microsolvation of fluoroethylenes by CO2

2019 Spring National Meeting

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