\\ Species Tag:        &   31010 & Name:&  CH$_3$CH$_2$D g.s and  $\nu_{18}$        
\\ Version:            &       1 & & 1D-Ethane
\\ Date:       &  Dec. 2014      & & 
\\ Contributor:&  A.M. Daly, B. J. Drouin     &  & 
\\             &                 & & 
\\ Lines Listed:       &   38764 & Q(300.0)=&   32720.6379
\\ Freq. (GHz) $<$     &    2000 & Q(225.0)=&   18267.0606
\\ Max. J:             &     50  & Q(150.0)=&    8698.1224
\\ LOGSTR0=            &   -12.0 & Q(75.00)=&    2858.7608
\\ LOGSTR1=            &   -12.0 & Q(37.50)=&    1008.6979 
\\ Isotope Corr.:      &       0 & Q(18.75)=&     359.2054
\\ Egy. (cm$^{-1}$) $>$&     0.0 & Q(9.375)=&     128.8711				  
\\ $\mu_a$ = & 0.015         (gs)& A=& 69653.392
\\ $\mu_b$ = & 0.015             & B=& 18859.082
\\ $\mu_c$ = &                   & C=& 18214.160
\headend 										
											
Initial work by  E. Hirota, Y. Endo, S. Saito, J.L. Duncan, Microwave spectra of deuterated ethanes: 
J. Mol. Spectrosc. 89 (1981) 285-295  measured the rotational spectrum 
in the ground state of CH$_3$CH$_2$D up to 160 GHz including 12 pairs 
of $a-$ and 15 pairs of $b-$ dipole transitions that were split into two hindered rotation components ($A$ and $E$).

Subsequent measurements made at JPL by A.M.Daly, B.J. Drouin, P. Groner, S.Yu and J. C. Pearson (JMS in press) report
the pure rotational spectrum of the ground and first excited torsional state $\nu_{18}$ of CH$_3$CH$_2$D, 
with measurements made up to 1.6 THz for the ground state and 1.1 THz for the $\nu_{18}$ state.  The energy 
differences between the $A$ and $E$ torsional substates, $\Delta$E($E$-$A$), of 74.167(18) and -3382.23(34) MHz
for the ground and excited states, respectively.   Using these energy differences
and the overtone transitions $\Delta \nu_{18}$ = 2 from Raman measurements in the literature  J.M. Fern\'{a}ndez-S\'{a}nchez,
S. Montero, J. Chem. Phys. 94 (1991) 7788-7800, 
the coefficients V$_3$ and V$_6$ of the potential function of the internal rotation in CH$_3$CH$_2$D 
were determined as V$_3$= 1004.56(4) cm$^{-1}$ and V$_6$=  7.09(12) cm$^{-1}$.


The dipole moment components are estimated to be equal components of the deuteromethane dipole (J. K. G. Watson, M. Takami, and T. Oka, 1979, J. Chem. Phys., 70, 5376).


\begin{table}[h]
\begin{tabular*}{\hsize}{@{\extracolsep{\fill}}c|c|c|c}
    & gs   &  v$_{18}$ = 1 \\
\hline
A  & 0    &   3        \\
E  & 1,2  &   4,5      \\
\end{tabular*}
\end{table}

The partition function at 300 K was calculated with a sum-over-states up to $J$ of 80, and does include other vibrational states below 990 cm$^{-1}$.  The summation is truncated at $J$ = 50.