  The charge transfer from an adatom to a semiconductor substrate of
one-dimensional quantum dot array is evaluated theoretically. Due to the Van
Hove singularity in the density of electron states at the band edges, the
charge transfer decay rate is enhanced nonanalytically in terms of the coupling
constant $g$ as $g^{4/3}$. The optical absorption spectrum for the ionization
of a core level electron of the adatom to the conduction band is also
calculated. The reversible non-Markovian process and irreversible Markovian
process in the time evolution of the adatom localized state manifest themselves
in the absorption spectrum through the branch point and pole contributions,
respectively.
