Smith, M.A.; Mantz, A.; Crawford, T.J.; Sung, K.; Benner, D.C.; Devi, V.M. LINE POSITIONS AND INTENSITIES FOR THE ν12 BAND OF 13C12CH6. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014.

High-resolution, high signal-to-noise spectra of 

mono-substituted $^{13}$C-ethane ($^{13}$C$^{12}$CH$_6$) in the 12.2 $\mu$m region 

were recorded with a Bruker IFS 125HR Fourier transform spectrometer. The spectra were 

obtained for four sample pressures at three different temperatures between 130 and 208 K 

using a 99$\%$ $^{13}$C-enriched ethane sample  

contained in a 20.38-cm long coolable absorption cell\footnote{K.~Sung, A.~W.~Mantz, 

 L.~R.~Brown, \textit{et al.}, \textit{J. Mol. Spectrosc.}

 \underline{\textbf{162}} (2010) 124-134.}. A multispectrum nonlinear least squares 

fitting technique\footnote{D.~C.~Benner, 

 C.~P.~Rinsland, V.~Malathy Devi, M.~A.~H.~Smith and 

 D.~Atkins, \textit{JQSRT} \underline{\textbf{53}} (1995) 705-721.} was used to 

fit the same intervals in the four

spectra simultaneously to determine line positions and intensities. Similar to our previous 

analyses of $^{12}$C$_2$H$_6$ spectra in this same region\footnote{V.~Malathy Devi, 

 C.~P.~Rinsland, D.~Chris Benner,   \textit{et al.}, \textit{JQSRT} \underline{\textbf{111}} 

 (2010) 1234-1251; V.~Malathy Devi, D.~Chris Benner, C.~P.~Rinsland,  \textit{et al.},

 \textit{JQSRT} \underline{\textbf{111}} (2010) 2481-2504.}, constraints were applied 

to accurately fit each pair of doublet components arising from torsional Coriolis interaction 

of the excited $\nu_{12} = 1$ state with the nearby torsional $\nu_6 = 3$ state. Line intensities 

corresponding to each spectrum temperature (130 K, 178 K and 208 K) are reported 

for 1660 $\nu_{12}$ absorption lines for which the assignments are known, and integrated 

intensities are estimated as the summation of the measured values. The measured line positions 

and intensities (re-scaled to 296 K) are compared with values in recent editions of 

spectroscopic databases.\footnote{Research described 

in this paper was performed at Connecticut College, the College of William and Mary, 

NASA Langley Research Center and the Jet Propulsion Laboratory, California 

Institute of Technology, under contracts and cooperative agreements with the National 

Aeronautics and Space Administration.}