\begin{table}%t3
%\centering
\par
\caption{\label{rates}Conversion fraction of CO into H$_2$CO and CH$_3$OH
as a function of $T$ and H/CO.}
\par
\small \begin{tabular}{rllllllll}
\noalign{\smallskip}\hline\hline \noalign{\smallskip}
{$\frac{n({\rm H})}{n({\rm CO})}$} & \multicolumn{4}{c}{Temperature (K)} \\
& {12.0} &  {13.5} & {15.0} & {16.5}\\
\hline\noalign{\smallskip}
{H$_2$CO}\\
0.50 & $5.4 \times 10^{-1}$ & $2.4 \times 10^{-1}$ & $1.4 \times 10^{-1}$ & $3.0 \times 10^{-2}$ \\
0.75 & $3.7 \times 10^{-1}$ & $2.3 \times 10^{-2}$ & $1.7 \times 10^{-1}$ & $3.0 \times 10^{-2}$\\
1.00 & $1.8\times 10^{-1}$ & $2.1 \times 10^{-1}$ & $1.9 \times 10^{-1}$ & $4.0 \times 10^{-2}$\\
2.00 & $6.8 \times 10^{-3}$ & $4.3 \times 10^{-2}$ & $1.6 \times 10^{-1}$ \\
5.00 & $1.0   \times 10^{-5}$ & $1  \times 10^{-3}$ & $2.1 \times 10^{-2}$ \\
\hline
 {CH$_3$OH}\\
0.50 & $2.1 \times 10^{-1}$ & $1.8 \times 10^{-1}$ & $5.2 \times 10^{-2}$ & $8.5 \times 10^{-1}$ \\
0.75 & $5.4 \times 10^{-1}$ & $3.1 \times 10^{-1}$ & $1.1 \times 10^{-1}$ & $7.5 \times 10^{-1}$\\
1.00 & $9.9 \times 10^{-1}$ & $3.3 \times 10^{-1}$ & $1.1 \times 10^{-1}$ & $7.1 \times 10^{-1}$\\
2.00 & $1.0 \times 10^{0}$  & $8.6 \times 10^{-1}$ & $4.4 \times 10^{-1}$ \\
5.00 & $1.0 \times 10^{0}$  & $1.0 \times 10^{0}$  & $1.0 \times 10^{0}$\\
\hline
\end{tabular}
\end{table}