\begin{table}%t7
\caption{\label{tab7}Comparison of effective collision strengths ($\Upsilon$) for transitions among the lowest 7 levels of Ar~XVII. ($a{\pm}b \equiv$ $a\times$10$^{{\pm}b}$).
First row: Zhang \& Sampson (1987), Second row: present results.}
%\centering
\par
\begin{tabular}{rrlllllr}
\hline
\hline
\multicolumn{2}{c}{Transition} & \multicolumn{2}{c}{Temperature (K)} & \multicolumn{2}{c}{Transition} & 
\multicolumn{2}{c}{Temperature (K)} \\
\hline
  $i$ & $j$   &  2.33+6    & 1.17+7  &  $i$ & $j$  &  2.33+6    & 1.17+7  \\
\hline
    1 &    2  &  9.78-4    & 7.23-4 &      3 &    4  &  2.49-2    & 1.55-2  \\
    1 &    2  &  1.48-3    & 8.98-4 &      3 &    4  &  2.69-2    & 1.72-2  \\
    1 &    3  &  5.07-4    & 3.73-4 &      3 &    5  &  2.10-3    & 1.17-3  \\
    1 &    3  &  5.59-4    & 4.14-4 &      3 &    5  &  2.60-3    & 1.48-3  \\
    1 &    4  &  1.57-3    & 1.20-3 &      3 &    6  &  2.63-2    & 1.99-2  \\
    1 &    4  &  1.79-3    & 1.35-3 &      3 &    6  &  2.79-2    & 2.18-2  \\
    1 &    5  &  1.64-3    & 1.75-3 &      3 &    7  &  1.34-2    & 7.15-3  \\
    1 &    5  &  1.83-3    & 1.89-3 &      3 &    7  &  1.44-2    & 8.21-3  \\
    1 &    6  &  2.53-3    & 1.86-3 &      4 &    5  &  1.89-2    & 2.14-2  \\
    1 &    6  &  2.70-3    & 2.06-3 &      4 &    5  &  1.48-2    & 1.78-2  \\
    1 &    7  &  5.31-3    & 7.15-3 &      4 &    6  &  9.17-2    & 6.40-2  \\
    1 &    7  &  5.34-3    & 7.25-3 &      4 &    6  &  9.88-2    & 7.14-2  \\
    2 &    3  &  2.09-1    & 2.67-1 &      4 &    7  &  3.88-2    & 2.16-2  \\
    2 &    3  &  1.88-1    & 3.04-1 &      4 &    7  &  4.24-2    & 2.52-2  \\
    2 &    4  &  6.09-1    & 7.78-1 &      5 &    6  &  1.06-2    & 5.86-3  \\
    2 &    4  &  5.54-1    & 8.90-1 &      5 &    6  &  1.35-2    & 7.56-3  \\
    2 &    5  &  9.22-3    & 5.80-3 &      5 &    7  &  6.17-1    & 7.98-1  \\
    2 &    5  &  9.96-3    & 6.24-3 &      5 &    7  &  5.72-1    & 9.12-1  \\
    2 &    6  &  9.96-1    & 1.26-0 &      6 &    7  &  6.15-2    & 3.46-2  \\
    2 &    6  &  9.21-1    & 1.49-0 &      6 &    7  &  6.82-2    & 4.12-2  \\
    2 &    7  &  2.72-2    & 1.99-2 &        &       &            &         \\
    2 &    7  &  2.83-2    & 2.36-2 &        &       &            &         \\
\hline                                                                                              
\end{tabular}                
\end{table}