Data-Centered Analysis of Mixed CO₂/Alkene Clusters up to Heptamers Using Fourier-Transform Microwave Spectroscopy and Computational Methods

Microwave spectroscopic datasets containing transitions for up to nine unique molecular clusters within a single broadband spectrum have been deconvoluted and assigned. Two chirped-pulse Fourier-transform microwave (CP-FTMW) spectra were recorded with different sample concentrations for each CO₂/alkene mixture analyzed. Intensities of rotational transitions of different cluster species were found to vary reproducibly with sample concentration across a full CP-FTMW spectrum, allowing implementation of a simple data-centered approach to identify transitions belonging to different clusters. Formulae have been assigned and likely structural arrangements identified using a combination of spectroscopic data and computational methods. Results for trifluoroethylene (C₂HF₃) and hexafluoropropene (C₃F₆) clusters, (C₂HF₃)_x(CO₂)_y (x = 1-2; y = 1-6) and (C₃F₆)_x(CO₂)_y (x = 1, y = 1-3), will be presented, along with preliminary data for complexes of CO₂ with propene (C₃H₆) and 3-fluoropropene (C₃H₅F).