\begin{table}%t2
%\centering
\par
\caption{\label{fitRate_tab}Analytical fit parameters for the PAH carbon atom loss rate constant, 
         calculated for electron and ion collisions.}
\begin{tabular}{l c c c c c c c}     
\hline\hline
\noalign{\smallskip}
\multicolumn{2}{c}{Fitting function}  &\multicolumn{6}{c}{$f(T) = a+b~T+c~T^{2}+d~T^{3}+e~T^{4}+f~T^{5}$}  \\ 
\hline
              &    &  $a$  &  $b$  &  $c$  &  $d$  &  $e$  &  $f$  \\
\hline
                 &  Electrons   &  2136.83  & 1632.17   & --499.822  & 76.4347 & --5.82964 & 0.177174  \\
                 &     H        &  --1896.69 & 1480.8    & --462.733  & 71.8957 & --5.54719 & 0.169996  \\
$N_{\rm C} = 50$  &     He       &  --971.448 & 770.259   & --245.561  & 38.8995 & --3.05787 & 0.0954303 \\
                 &     C        &  --704.392 & 551.313   & --175.063  & 27.6506 & --2.16871 & 0.0675643 \\
\hline
                 &  Electrons   &  --2255.38 & 1681.45   & --503.451  & 75.4339 & --5.64956 & 0.168959  \\
                 &     H        &  --1645.64 & 1257.06   & --384.309  & 58.4103 & --4.41007 & 0.132356  \\
$N_{\rm C} = 100$ &     He       &  --945.901 & 747.921   & --237.984  & 37.6808 & --2.96613 & 0.0928852 \\ 
                 &     C        &  --711.244 & 558.48    & --177.983  & 28.2547 & --2.23145 & 0.0701374 \\      
\hline
                 &  Electrons   & --2234.37  & 1597.71   & --459.647  & 66.332  & --4.79841 & 0.139019  \\
                 &     H        &  --1473.64 & 1109.01   & --334.292  & 50.1417 & --3.74133 & 0.111164  \\
$N_{\rm C} = 200$ &     He       &  --963.188 & 765.639   & --245.054  & 39.0745 & --3.10123 & 0.0980047 \\
                 &     C        & --738.791  & 584.928   & --187.884  & 30.0819 & --2.39748 & 0.0760639 \\ 
\hline
\end{tabular}
\end{table}