Application of Intensity Ratios to Disentangle Rotational Spectra of Large Molecular Clusters: Trifluoroethylene with up to 6 CO2 Molecules.

A generalizable method of intensity ratio analysis has facilitated identification and deconvolution of rotational spectra for nine mixed trifluoroethylene (TFE)/CO2 clusters, (TFE)m(CO2)n, within a single spectroscopic data set. Molecular complexes with m = 1-2 and n = 1-6 have been investigated using chirped-pulse (CP) Fourier-transform microwave (FTMW) spectroscopy. Collection of two spectra with different CO2 concentrations allowed determination of intensity ratios of rotational transitions, which were then correlated with cluster size and formula. The wide composition range of observed TFE/CO2 clusters provides an abundance of data with which to benchmark computational methods for determining compositions and energy ordering of large mixed clusters. Initial computational structural results for experimentally observed species are also presented.