\begin{table}%t1
%\centering
\par
\small\caption{Relative intensities (PIY) and kinetic energy~$U_0$ release by fragments in the
methanol mass spectra, as a function of photon energy (at 100, 288, 292 and 310~eV).
Only fragments with intensity $>$0.1\% were tabulated. The estimated experimental
error was below 10\%.} \label{tab:piy}
\begin{tabular}{ l l l r r r r }
\hline \hline
\multicolumn{2}{c}{Fragments}    &  & \multicolumn{4}{c}{PIY(\%) / $U_0$ (eV)}\\
\cline{1-2}  \cline{4-7}
 $m/q$ & Attribution &  & 100~eV  & 288~eV  & 292~eV & 310~eV \\
\hline
1& H$^+$ &  & 13.7 / 2.2  & 17.3 / 2.9  & 17.0 / 3.0 & 19.1 / 3.8  \\
2& H$_2^+$  &  & 1.3 / 1.5 & 1.3 / 3.0   & 1.4 / 2.9& 1.3 / 1.1  \\
3& H$_3^+$ &  & 0.5 / 0.98 & 0.4 / 2.4   & 0.5 / 2.0& 0.6 / 0.18 \\
12& C$^+$ &  & 1.9 / 0.61  & 2.9 / 0.98  & 3.0 / 0.70& 4.9 / 0.50  \\
13& CH$^+$ &  & 2.8 / 0.37 & 2.8 / 0.78  & 2.8 / 0.78& 4.9 / 0.78  \\
14& CH$_2^+$ &  & 4.6 / 0.43 & 4.8 / 0.35  & 4.9 / 0.35    & 5.1 / 0.34 \\
15& CH$_3^+$ &  & 10.1 / 0.14 & 9.9 / 0.14  & 9.9 / 0.15    & 8.3 / 0.19  \\
16& O$^+$ &  & 1.4 / 1.2 & 1.4 / 2.2   & 1.6 / 1.59    & 2.4 / 1.1 \\
17& OH$^+$ &  & 2.9 / 0.69     & 2.2 / 0.28  & 2.6 / 0.98    & 3.3 / 1.7 \\
18& H$_2$O$^+$ &  & 1.6 / 0.05     & 1.5 / 0.03  & 1.6 / 0.04    & 1.1 / 0.12  \\
28& CO$^+$ &  & 3.1 / 0.14     & 3.8 / 0.05  & 3.8 / 0.10    & 4.4 / 0.21 \\
29& COH$^+$ or HCO$^+$     &  & 20.0 / 0.13    & 18.6 / 0.10 & 18.3 / 0.11   & 17.9 / 0.13 \\
30& HCOH$^+$ or H$_2$CO$^+$ &  & 2.3 / 0.05     & 2.4 / 0.07  & 2.4  / 0.07   & 2.0 / 0.07 \\
31& H$_2$COH$^+$&  & 17.3 / 0.04    & 16.2 / 0.05  & 15.9 / 0.06  & 13.8 / 0.07  \\
32& CH$_3$OH$^+$&  & 15.8 / 0.03    & 13.9 / 0.03  & 13.8 / 0.03  & 10.8 / 0.03 \\
\hline
\end{tabular}
\end{table}