FIRST HIGH RESOLUTION IR SPECTRA OF 2-D1-PROPANE. THE ν9 (A1) B-TYPE BAND NEAR 367.2389 cm−1.

This is a further report in a project to record high resolution IR data of the $^{13}$C and D substituted isotopologues of propane (see talks FA04, FA05 and TK08 at 2017 ISMS). Initially in CLS Cycle 23 (Jan-Jun, 2015) we recorded spectra of the \nub{26} (B$_{2}$) C-Type band whose corresponding band in C$_{3}$H$_{8}$ is observed in Titan's Atmosphere.That band and others seen in the 550-950 \wn region were too perturbed by complex torsional splittings for analysis at this time. In this talk will give details on the first high resolution ($\Delta$$\nu$ = 0.00096 \wn) IR investigation of the spectrum in the Far-IR region. We recorded spectra during Cycle 25 (Jan-Jun, 2017) of the \nub{9} (A$_{1}$) CCC skeletal bending mode near 367.2389 \wn. This has a B-type band structure and appears unperturbed. Spectra were recorded at pressures of 0.014, 0.056, 3.995 \& 8.087 Torr in a 72m optical path at room temperature. We used the Bruker IFS-125HR on the Far-IR beamline of the CLS. The spectra were assigned both traditionally and with the aid of the PGOPHER program of Colin Western.\footnote{C. Western, J. Quant. Spectrosc. \& Rad. Transf. \textbf{186}, 221 ff. (2017).} We were able to assign over 8100 lines with up to K = 35 and J = 60 using both the 4 and 8 Torr data sets. The only available MW data on this molecule are the seven K = 0, J = 0-6 lines from Lide.\footnote{Lide, J.Chem. Phys. \textbf{33}, p.1514ff. (1960).}. We therefore had to use the present data to determine a new set of ground state constants that included centrifugal distortion terms for this molecule. We compare these experimentally determined values with both Lide's A, B, C values and the recent calculated \textit{ab initio} values of Villa, Senent \& Carvajal.\footnote{Villa, Senent \& Carvajal, PCCP \textbf{15}, 10258 (2013).} Upper state constants have also been been derived that provide a good simulation of the observed spectra. The hope is that this data will be useful in identifying isotopic propane lines in Titan and other astrophysical objects