\begin{table}%ta3 
\caption{\label{tab:reache}List of reactions for the helium chemistry.}
%%\centering

\par
\small
\begin{tabular}{l l l l}
\hline
\hline
& Reaction & & Reaction\\
\hline
He1 & ${\rm He^{++} + e^- \rightarrow He^+ + \gamma}$ & He2 & ${\rm He^+ + \gamma \rightarrow He^{++} + e^-}$\\
He3 & ${\rm He^+ + e^- \rightarrow He + \gamma}$ & He4 & ${\rm He + \gamma \rightarrow He^+ + e^-}$\\
He5 & ${\rm He + H^+ \rightarrow He^+ + H}$ & He6 & ${\rm He^+ + H \rightarrow He + H^+}$\\
He7 & ${\rm He + H^+ \rightarrow HeH^+ + \gamma}$ & He8 & ${\rm He + H_2^+ \rightarrow HeH^+ + H}$\\
He9 & ${\rm He^+ + H \rightarrow HeH^+ + \gamma}$ & He10 & ${\rm HeH^+ + H \rightarrow He + H_2^+}$\\
He11 & ${\rm HeH^+ + e^- \rightarrow He + H}$ & He12 & ${\rm HeH^+ + H_2 \rightarrow H_3^+ + He}$\\
He13 & ${\rm HeH^+ + \gamma \rightarrow He + H^+}$ & He14 & ${\rm HeH^+ + \gamma \rightarrow He^+ + H}$\\
\hline
\end{tabular}
\end{table}