\begin{table}%t1
%\centering
\par
\caption{\label{tab:bands}The wavenumbers ($\tilde\nu$ in \cm) of the most prominent peaks of the heterocycles with their assignments, used to monitor the UV~photodestruction. $\nu$ denotes a stretching mode, $\beta$ is a bending mode and $\tau$ refers to a torsion mode. Taken from {\it a} \citet{destexhe} and {\it b} \citet{morrison}.}
\begin{tabular}{llllll}
\hline\hline
	\multicolumn{2}{l}{Pyridine$^a$} & \multicolumn{2}{l}{Pyrimidine$^a$} & \multicolumn{2}{l}{s-Triazine$^b$} \\
	$\tilde\nu$ (\cm) & mode description & $\tilde\nu$ (\cm) & mode description & $\tilde\nu$ (\cm) & mode description \\
	\hline
	702 	&$\tau$-ring            &621  &$\beta$-ring           &680  &$\beta$-ring \\
	1031	&$\beta$-ring           &719  &$\tau$-ring            &738  &$\nu$-ring \\
	1441	&$\nu~$CC, $\beta~$CH &1400 &$\beta~$CH, $\nu~$CN &1416 &$\nu~$CH \\
	1582	&$\nu~$CC              &1571 &$\nu~$CN, $\nu~$CC   &1552 &$\beta~$N out-of-plane \\
	3008	&$\nu~$CH              &3042 &$\nu~$CH              &     & \\
	\hline
	\end{tabular}
\par
\end{table}