\begin{table}%t3
\par
  \caption {\label{tab:dr}Dissociative recombination branching ratios employed in the
    present work.}  %\centering
\par
  %\centering
\par
  \begin{tabular}{l c c l r r r c}
    \hline
    \hline
    Ion & \multicolumn{2}{c}{Total rate\tfm{a}} & Products & \multicolumn{3}{c}{Model} & \\ %Ref.~\tfm{b} \\ %  1 & Model 2 & Model 3 \\ 
        & $\gamma$ & $\beta$ & & 1 & 2 & 3 \\\hline
    N$_2$H$^+$\tfm{b} & 1.00(--7) & --0.5   &  {N$_2$ + H}      & 100\% &  90\% &  90\%\\
              & & &  {NH + H}  & 0\%   &  10\% &  10\% \\
    {NH$_2^+$}\tfm{c} & 3.00(--7) & --0.5   &  {N + H + H}& 57\% &  &   \\
              &                & & {N + H$_2$}      &  4\% &  &     \\
              &                & & {NH + H}      & 39\% &  &     \\
     {NH$_3^+$} & 3.10(--7) & --0.5 &  {NH  + H + H} & 50\% \\
              & &            &  {NH$_2$ + H}     & 50\% \\
    NH$_4^+$\tfm{d} & 9.40(--7) & --0.6   &  {NH$_3$ + H}     & 85\%  &  85\% &  95\%  \\
              & & &  {NH$_2$ + H$_2$}    &  2\%  &   2\% &   2\% \\
              & & &  {NH$_2$ + H + H} & 13\%  &  13\% &   3\% \\
    \hline
%    \ce{NH + C+}  & 4.60(-9) & -0.5 & \ce{CN+ + H} \\
%    \ce{NH2 + C+} & 2.70(-9) & -0.5 & \ce{HCN+ + H} \\
%    \ce{NH3 + C+} & 2.15(-9) & -0.5 & \ce{HCN+ + H}  \\
%                  & &               & \ce{H2CN+ + H} \\
%                  & &               & \ce{NH3+ + H}  \\
  \end{tabular}
    \tfoot{\tft{a}{Reaction rates are written as $k=\gamma(T/300)^\beta$
      in cm$^3$~\s.}
    \tft{b}{\cite{molek2007}}, 
    \tft{c}{\cite{thomas2005}}, 
    \tft{d}{\cite{ojekull2004}.}}
\end{table}