\begin{table}%t1
\caption{\label{energies}Energy absorbed per unit mass of the polystyrene samples exposed to ion 
irradiation.}                   
%\centerline
{\small          
\begin{tabular}{c  c c c  c c c c}     
\hline\hline \noalign{\smallskip}                
\multicolumn{4}{c}{$2.55\times 10^{-2}$~$\mu$m; 400~keV Ar$^{++}$ } &
\multicolumn{4}{c}{$5.71\times 10^{-2}$~$\mu$m; 200~keV H$^{+}$}\\ 
\hline \noalign{\smallskip}                    
$S.P.$ total 	& \multicolumn{3}{c}{$1.58\times 10^{-12}$} & 
\multicolumn{4}{c}{$1.71\times 10^{-13}$}\\
$S.P.$ elastic & \multicolumn{3}{c}{$4.30\times 10^{-13}$} &
\multicolumn{4}{c}{$1.31\times 10^{-16}$}\\
$S.P.$ inelastic & \multicolumn{3}{c}{$1.15\times 10^{-12}$} &
\multicolumn{4}{c}{$1.71\times 10^{-13}$}\\
\hline
$fl.$  & $D$ tot. & $D$ el. & $D$ inlel. & $fl.$ & $D$ tot. &
$D$ el. & $D$ inel. \\
\hline\noalign{\smallskip}
$6.3\times 10^{12}$ & 1.5 & 0.4 & 1.1 &	 $6.3\times 10^{13}$ & 1.6 & 0.001 & 1.6 \\ 
$3.8\times 10^{13}$ & 9.1 & 2.5 & 6.6 &	 $2.5\times 10^{14}$ & 6.6 & 0.005 & 6.6 \\ 
$7.5\times 10^{13}$ & 18.3 & 5.0 & 13.3 &	 $2.0\times 10^{15}$ & 52.7 & 0.040 & 52.7 \\
$1.5\times 10^{14}$ & 36.5 & 9.9 & 26.6 &	 $4.0\times 10^{15}$ & 105.5 & 0.080 & 105.4 \\ 
$6.0\times 10^{14}$ & 146.0 & 39.7 & 106.3 &   $8.0\times 10^{15}$ & 211.0 & 0.161 & 210.8 \\
$5.2\times 10^{15}$ & 1274.8 & 346.8 & 928.0 & $1.6\times 10^{16}$ & 422.0 & 0.321 & 421.6 \\  
\hline                  
\end{tabular}}
\tablefoot{$S.P.$ -- stopping power (eV~cm$^{2}$~mol$^{-1}$), $fl.$ -- fluence
(ions/cm$^{2}$), $D$ -- dose (eV/(16 u)).}
\end{table}