\begin{table}%t1
\caption{\label{table1}Infrared absorption bands and assignments of NH$_{3}$ and
CO$_{2}$, in pure solids and in NH$_{3}$:CO$_{2}$ ice mixtures at 10 K.}
\par
%\centerline
 {
\begin{tabular}{lccc}
\hline\hline\\[-3.5mm]
\multicolumn{1}{c}{Assignment}&\multicolumn{2}{c}{Wavenumbers
(cm$^{-1}$)}\\\hline
NH$_{3}$ \cite{Ferraro80} & Solid & 1:1 ratio \\
$\nu_3$ & 3375 &3410; 3379  \\
$2\nu_4$ & 3290 & 3309 \\
$\nu_1$ & 3210  & 3219 \\
$\nu_4$ & 1625  & 1626\\
$\nu_2$ & 1075  &1064\\
$\nu_5$ & 530  &   \\\hline
CO$_{2}$ \cite{Gerakines95}& Solid & 1:1 ratio\\
$(\nu_1+\nu_3)$ & 3708 &3700 \\
$(2\nu_2+\nu_3)$ & 3600 &3594 \\
$(\nu_3)$ $\nu_{\rm as}$~CO$_{2}$ & 2337 &2333 \\
$(\nu_3)$ $\nu_{\rm as}$~$^{13}$CO$_{2}$ & 2282 & 2278  \\
$(\nu_2)$ $\delta$~CO$_{2}$ & 654 & 658 \\
\hline
\end{tabular}}
 \medskip
\par
Vibration mode: stretching ($\nu$), bending ($\delta$).\\
Indication:  asymmetric (as), symmetric (s).
\end{table}