\begin{table}%t
\caption{\label{CCNrates}Rate coefficients for the C + C$_n$ reactions.}
%\centerline
 {\small 
 \begin{tabular}{lcccc}
\hline \hline
Reaction & \multicolumn{2}{c}{osu.2003 rate coefficient} & \multicolumn{2}{c}{New rate coefficient} \\
 & $\alpha^{1}$ &  $\beta^{1}$ & $\alpha$ &  $\beta$ \\
\hline\noalign{\smallskip}
$\rm C + C_2 \longrightarrow C_3 + h\nu$ & -- & -- & $(3 \pm 2) \times 10^{-16}$ & --1 \\
$\rm C + C_3 \longrightarrow C_4 + h\nu$ & $1.0\times 10^{-10}$ & 0 & $(4\pm 3)\times 10^{-14}$ & --1 \\
$\rm C + C_4 \longrightarrow C_2 + C_3$ & $1.0\times 10^{-13}$ & 0 & $(0.9 \pm 0.6)\times 10^{-10}$ & 0 \\
$\rm C + C_5 \longrightarrow C_6 + h\nu$ & $1.0 \times 10^{-10}$ & 0 & -- & -- \\
$\rm C + C_5 \longrightarrow C_3 + C_3$ & -- & -- & $(1.2\pm 0.8)\times 10^{-10}$ & 0 \\
$\rm C + C_6 \longrightarrow C_2 + C_5$ & $1.0\times 10^{-13}$ & 0 & $(0.5\pm 0.3) \times 10^{-10}$ & 0 \\
$\rm C + C_6 \longrightarrow C_3 + C_4$ & -- & -- & $(0.5\pm 0.3) \times 10^{-10}$ & 0 \\
$\rm C + C_7 \longrightarrow C_8 + h\nu$ & $1.0 \times 10^{-10}$ & 0 & -- & -- \\
$\rm C + C_7 \longrightarrow C_3 + C_5$ & -- & -- & $(1.4 \pm 0.8) \times 10^{-10}$ & 0 \\
$\rm C + C_8 \longrightarrow C_4 + C_5$ & -- & -- & $(0.4 \pm 0.2)\times 10^{-10}$ & 0 \\
$\rm C + C_8 \longrightarrow C_3 + C_6$ & -- & -- & $(0.4 \pm 0.2)\times 10^{-10}$ & 0 \\
$\rm C + C_8 \longrightarrow C_2 + C_7$ &  $1.0 \times 10^{-13}$ & -- & $(0.4 \pm 0.2)\times 10^{-10}$ & 0 \\
\hline
\end{tabular}}
\smallskip
$^1$ Rate coefficients in units of cm$^{3}$~s$^{-1}$ given by $k = \alpha \times (T/300)^{\beta}$.\end{table}