\begin{table}%t1


  \caption {\label{tab1}Peak position and assignments for unirradiated C$^{18}$O$_{2}$ ice.}
  %\centerline
 {
  \begin{tabular}{l l}
  \hline \hline
  Position (cm$^{-1}$) & Assignment \\
  \hline
  3627$^1$                 & 2$\nu_{2}$ + $\nu_{3}$ \\
  3518$^1$                 & $\nu_{1}$ + $\nu_{3}$  \\
  2311                 & $\nu_{3}$ \\
  2247                 & $\nu_{3}$; $^{13}$C$^{18}$O$_{2}$ \\
  650                  & $\nu_{2}$ \\
  \hline
    \end{tabular}}
     \smallskip
    $^{1}$ Fermi resonance.
\end{table}