\begin{table}%t12
\caption{\label{TabPIRSize}Estimates of the post-shock photoionized region thickness $l_{\rm
PSPIR}$ from several fine-structure line ratios to the 5007~\AA\
line. }
%\centerline
 {\small \begin{tabular}{llll}
\hline\hline\noalign{\smallskip}
Spectral line & $\varepsilon$, erg cm$^3$/s & $n($ion$)/n($elem$)$
          & $l_{\rm PSPIR}$, cm \\
\hline\noalign{\smallskip}
{}[\ion{O}{i}]   63.19~$\mu$m & $1.2\times10^{-24}$ & 0.94& $1.2\times10^{11}$ \\
%
{}[\ion{Si}{ii}] 34.81~$\mu$m & $1.3\times10^{-23}$ & 1.0 & $2.1\times10^{11}$ \\
%
{}[\ion{Ar}{ii}] 6.985~$\mu$m & $2.0\times10^{-21}$ & 0.4 & $2.0\times10^{11}$ \\
%
{}[\ion{Fe}{ii}] 17.94~$\mu$m & $4.0\times10^{-23}$ & 1.0 & $3.0\times10^{11}$ \\
%
   \ion{O}{i}    7774~\AA     & $1.3\times10^{-24}$ & 0.06& $8.0\times10^{10}$ \\
\hline
\end{tabular}}
\medskip
{Notes}: estimates made for post-shock PIR electron density
$n_{\rm e} = 5 \times 10^5$~cm$^{-3}$ and temperature $T_{\rm
e}=1500$~K. Oxygen abundance have been taken to be $n_{\rm O}/n_{\rm
t}=0.6$ (see Sect.~\ref{SecChEx}), other abundances as in
Table~\ref{TabAbund}.
\end{table}