Vibrational overtone spectra and interactions of C2H4 and H2CCHCH3 in liquid Kr

Vibrational overtone spectra of ethene and propene dissolved in liquid krypton at 120 K have been recorded between 5000 and 16500 cm−1. Spectral regions for the first four overtones were measured using a Fourier transform spectrophotometer. The fifth overtone (Δυ = 6) spectra in liquid Kr were recorded with a double beam (pump-probe) thermal lens technique. Local-mode parameters were calculated for C-H oscillators in solution and compared with gas phase local mode parameters. The bandwidth (Δω1/2) of the absorption bands of ethene correlate with the magnitude of the collision frequency with the solvent atoms. For propene, the shapes of the absorption bands in gas phase and in liquid krypton are similar. Density functional theory calculations of the structural parameters and C-H vibrational frequencies of propene in gas phase and in solution are reported. Frequency shifts (Δω) with respect to gas phase results are attributed to changes in harmonic frequency and anharmonicity of the particular C-H bond of the sample dissolved in liquid krypton.