\begin{table}%t2
\par
%\centering
\par
\caption{\label{tab:n_cr}Einstein coefficients, upper level energies and critical densities 
for the range of temperatures considered in this work.}
%\small 
\begin{tabular}{lccrrc} 
\hline \hline
Molecule  & Transition &   Frequency & $A_{ij}$      
&  $E_\emr{up}$  & $n_\emr{crit}$  \\
&      &    (GHz)        &      (s$^{-1}$) &      (K)   
&        (cm$^{-3}$)       \\
\hline\noalign{\smallskip}
o-\NHHD & $1_{1,1}$--$1_{0,1}$ & 85926.2780 &  7.82e-6  &   20.68  & 4.2 10$^6$\\
o-\fNHHD & $1_{1,1}$--$1_{0,1}$ & 86420.1959 & 7.96e-6 & 20.63 & 4.2 10$^6$ \\
p-\fNHHD & $1_{1,1}$--$ 1_{0,1}$ & 109284.9021 & 1.61e-5  & 21.18 &8.8 10$^6$\\
\hline
\end{tabular}
\end{table}