  The behavior of a two level atom in a half-cavity, i.e. a cavity with one
mirror, is studied within the framework of a one dimensional model with respect
to spontaneous decay and resonance fluorescence. The system under consideration
corresponds to the setup of a recently performed experiment [J. Eschner
\textit{et. al.}, Nature \textbf{413}, 495 (2001)] where the influence of a
mirror on a fluorescing single atom was revealed. In the present work special
attention is paid to a regime of large atom-mirror distances where intrinsic
memory effects cannot be neglected anymore. This is done with the help of delay
differential equations which contain, for small atom-mirror distances, the
Markovian limit with effective level shifts and decay rates leading to the
phenomenon of enhancement or inhibition of spontaneous decay. Several features
are recovered beyond an effective Markovian treatment, appearing in
experimental accessible quantities like intensity or emission spectra of the
scattered light.
