\begin{table}%t1
%\centering
\par
\caption{Log of experiments for GC--MS analysis.}
\label{logGC}
\begin{tabular}{cccccc}   
\hline \hline
Experiment & Ice & UV dose & Molecular ion mass & Assigned carrier & Integ. area\\%& Peak height\\
 & H$_2$O:NH$_3$:CH$_3$OH:CO:CO$_2$ & photon molec.$^{-1}$ & amu & & (relat. to HMT) \\  \hline %& (relat. to HMT)\\  
1 & 2:1:1:1:1 & 0.15 & 140 & HMT & 100 \\   
  & &           & 154    & HMT--CH$_3$ & 0.005\\% & 0.05$^1$ \\
  & &           & 156    & HMT--OH & 0.04, 0.02 \\ %0.4,0.2$^1$ \\ 
  & &           & 198    & HMT--CHOH--CHO & 0.04 \\ \hline%0.4 \\ \hline
2 & 2:1:1:1:1$^2$ & 0.45 & 144 & HMT & 100 \\   
  & &           & 160    & HMT--OH & 2.0 \\ \hline%13.0 \\ \hline
3 & 2:1:1:1:1$^3$ & 0.28 & 140, 141, 142, 143, 144 & HMT & 100 \\   
  & &           & 156, 157, 158, 159 & HMT--OH & 4.0\\ \hline %24.0\\ \hline%second face 
4 & 2:1:1:0:1 & 0.15 & 140 & HMT & 100 \\   
  & &           & 154    & HMT--CH$_3$ & 0.07\\ %0.6 \\
  & &           & 156    & HMT--OH & 0.25\\ %& 2.0 \\ 
  & &           & 170    & HMT--CH$_2$OH & 0.03\\% 0.3 \\
  & &           & 183    & HMT--NH--CHO & 0.04\\ \hline%& 0.4 \\ \hline
5 & 2:1:1:0:1$^4$ & 0.15 & 146 & HMT & 100 \\   
  & &           & 161    & HMT--CH$_3$  & 0.02$^1$ \\%~0.5$^1$ \\
  & &           & 162    & HMT--OH & 1.2 \\%7.5 \\ 
  & &           & 177    & HMT--CH$_2$OH & 0.3\\%3.0 \\
  & &           & 190    & HMT--NH--CHO & 0.1\\ \hline%1.0 \\ \hline
6 & 2:0.2:1:0:1 & 0.28 & 140 & HMT & 100 \\   
  & &           & 154    & HMT--CH$_3$ & 0.01\\%0.1 \\
  & &           & 156    & HMT--OH & 0.20\\%1.9 \\ 
  & &           & 198    & HMT--CHOH--CHO & 0.07 \\ \hline% 0.7 \\
7 & 2:1:1:1:1$^{4,5}$ & 0.45 & 146 & HMT & 100 \\ %15 face III   
  & &           & 161    & HMT--CH$_3$ & 0.4 \\%2.4 \\
  & &           & 162    & HMT--OH & 12 \\%34.6  \\ 
  & &           & 206    & HMT--CHOH--CHO & 2.0\\% 9.9 \\ 
\hline
\end{tabular}
\begin{list}{}{}
\item[$^1$] Using hexane as solvent, undetected in methanol solution.
\item[$^2$] $^{15}$NH$_3$-labelled.
\item[$^3$] With $^{13}$CO, $^{13}$CO$_2$, $^{12}$CH$_3$OH.
\item[$^4$] $^{13}$C-labelled.
\item[$^5$] Using DMF--DMA derivatization.
\end{list}
\end{table}