\begin{table}%t4
%\centering
\par
\caption{\label{reactions}Surface reactions in the H, O and CO system.}
\small \begin{tabular}{lcll}
\hline \hline 
Reactants & &Products & $E_{\rm a}$(K) \\
\hline
H + H &$\rightarrow$& H$_2$ & \\
H + O &$\rightarrow$& OH &  \\
H + OH &$\rightarrow$& H$_2$O & \\
H + CO &$\rightarrow$& HCO & Table~\ref{Energies} \\
H + HCO &$\rightarrow$& H$_2$CO & \\
H + H$_2$CO &$\rightarrow$& H$_3$CO & Table~\ref{Energies} \\
H + H$_3$CO &$\rightarrow$& CH$_3$OH & \\
O + O &$\rightarrow$& O$_2$ &  \\
O + OH &$\rightarrow$& O$_2$ + H &  \\
 CO + OH &$\rightarrow$& CO$_2$ + H & 176 \\
 OH + H$_2$CO &$\rightarrow$& HCO + H$_2$O & \\
 OH + H$_3$CO &$\rightarrow$& H$_2$CO + H$_2$O & \\
\hline
\end{tabular}
\end{table}