\begin{table}%t2
\caption{Influence of the sticking coefficients. For reaction index $r$ see Table~\ref{tab:chemreak}.} 
\label{tab:alpha}
%\centerline
{\begin{tabular}{cccccc}\hline\hline\noalign{\smallskip}
{Index} $r$ &                        & {\#0}$^1$ & {\#1} & {\#2} & {\#3}$^2$\\
\hline\noalign{\smallskip}
1, 2, 3$^3$          & $\alpha^{\rm TiO_2}_{1,2,3}$ & 1   & 1 & 1 & 1\\
\hline
4               &  $\alpha^{\rm SiO_2}_4$      & 1 & 0.1 & 0.1  & 1  \\
5               &  $\alpha^{\rm SiO_2}_5$      & 1 & 0.1 & 0.01 & 0.01  \\
6 $^3$               &  $\alpha^{\rm SiO_2}_6$      & 1 & 0.1 & 0.1  & 1 \\
\hline\noalign{\smallskip}
7, 8, 9         &  $\alpha^{\rm Fe}_{7,8,9}$   & 1   & 1 & 1 & 1\\
\hline\noalign{\smallskip}
10, 11, 12      & $\alpha^{\rm Mg_2SiO_4}_{10\ldots 12}$ & 1 & 0.1 & 0.1 & 0.04\\
\hline\noalign{\smallskip}
13 $~\ldots~$ 17 $^3$ & $\alpha^{\rm Al_2O_3}_{13\ldots 17}$ & 1 & 1 & 1 & 1\\
                & & [dark & [light & [orange] & [red]\\
                & & blue] & blue]\\   
\hline
\end{tabular}}\medskip
\par
$^1$ Resembles Sect.~\ref{sec:Results}.
$^2$ The most extreme values given in Hashimoto (\cite{Hashimotoha1990}).
$^3$ No measurements in the literature. We assume $\alpha =1$ for TiO$_2$[s], Al$_2$O$_3$[s] and $\alpha^{\rm SiO_2}_4=\alpha^{\rm SiO_2}_6$.
\end{table}