First high-resolution infrared spectra of 2–13C-propane: Analyses of the ν26 (B2) c-type and ν9 (A1) b-type bands

Abstract

This paper presents the first high resolution (Δν = 0.00096 cm−1) IR investigation of 2–13C-propane. Spectra of the ν9(A1) CCC skeletal bending mode near 336.767 cm−1 (a b-type band) and the ν26(B2) methylene (CH2) rocking mode near 746.614 cm−1 (a c-type band) were recorded at the Canadian Light Source (CLS) synchrotron. The spectra were assigned both traditionally and with the aid of the pgopher program. As only limited microwave data are available for this molecule the present data was used to determine a new set of ground state constants that included centrifugal distortion terms. Upper state constants for both bands have been determined that provide a good simulation of the spectra. The analysis also included the strong a-type Coriolis resonance between the ν26 and 2ν9 states that causes strong perturbation-allowed transitions to appear in the spectrum. Lines of the 2ν9-ν9 hot band were also assigned and included in our analysis of the bending region. This data will be useful in identifying isotopic propane lines in Titan and other astrophysical objects.