High resolution infrared spectra of neopentane: Rovibrational analysis of bands at 8.3–6.4 μm

High resolution (0.0014 cm-1) infrared spectra of neopentane (2,2-dimethylpropane) have been recorded at 203 K at the Canadian Light Source. Spectra were recorded in the infrared (8.3-6.4 μm) with 8 m of optical path. Neopentane is a spherical top molecule with Td (tetrahedral) symmetry. A low temperature is favorable for a detailed rotational analysis of its fundamental bands. This study focuses on the analysis of 3 band systems of neopentane. The first system is a dyad consisting of a ν15 fundamental band and a ν7 + ν19 combination band located at 1472.5 and 1489 cm-1 , respectively. The second system is a ν16 fundamental band located at 1369.4 cm-1 with uncertain band origin. The third band system is a dyad of a ν17 fundamental and a ν8 + ν18 combination band. Only the ν17 fundamental band was analyzed in this last system due to the weaker intensity of the combination band. For all spectral simulations and calculations an 'XTDS' program based on tensorial formalism by the Dijon molecular spectroscopy group was used. A subprogram 'SPVIEW', paired with XTDS, was used for spectral assignment