  We study quantum dissipative effects due to the non-relativistic, bounded,
accelerated motion of a single neutral atom in the presence of a planar perfect
mirror, i.e. a perfect conductor at all frequencies. We consider a simplified
model whereby a moving `scalar atom' is coupled to a quantum real scalar field,
subjected to either Dirichlet or Neumann boundary conditions on the plane. We
use an expansion in powers of the departure of the atom with respect to a
static average position, to compute the vacuum persistence amplitude, and the
resulting vacuum decay probability. We evaluate transition amplitudes
corresponding to the excitation of the atom plus the emission of a particle,
and show explicitly that the vacuum decay probabilities match the results
obtained by integrating the transition amplitudes over the directions of the
emitted particle. We also compute the spontaneous emission rate of an
oscillating atom that is initially in an excited state.
