\begin{table}%t1
%\centering
\par
\caption{Chemical reaction rates.}\label{table1}
\begin{tabular}{lc}
\hline\hline
Reaction              & Reference \\
\hline
${\rm H^+   +   e^-  \to H     +   h\nu}$    &\citet{galli98}    \\  %H1
${\rm H     +   e^-  \to H^-   +   h\nu}$    &--                 \\  %H3
${\rm H^-   +   h\nu \to H     +   e^-}$     &--                 \\  %H4
${\rm H^-   +   H    \to H_2   +   e^- }$    &--                 \\  %H5
${\rm H^-   +   H^+  \to H_2^+ +   e^- }$    &--                 \\  %H6
${\rm H^-   +   H^+  \to 2H            }$    &--                 \\  %H7
${\rm H^+   +   H    \to H_2^+ +   h\nu}$    &--                 \\  %H8
${\rm H_2^+ +   H    \to H_2   +   H^+ }$    &--                 \\  %H10
${\rm H_2^+ +   e^-  \to 2H            }$    &--                 \\  %H11
${\rm H_2   +   H^+  \to H_2^+ +   H   }$    &--                 \\  %H15
${\rm H_2   +   e^-  \to 2H    +   e^- }$    &--                 \\  %H17
${\rm H_2   +   H    \to 3H            }$    &\citet{maclow86}   \\  %kdiss
${\rm H     +   e^-  \to H^+   +   2e^-}$    &\citet{abel97}     \\  %A1
${\rm H^-   +   e^-  \to H     +   2e^-}$    &--                 \\  %A14
${\rm H^-   +   H    \to 2H    +   e^- }$    &\citet{sk87}       \\  %S17
${\rm D^+   +   H_2  \to HD    +   H^+ }$    &\citet{galli98}    \\  %D8
${\rm H^+   +   HD   \to H_2   +   D^+ }$    &--                 \\  %D10
\hline
\end{tabular} 
\end{table}