We consider free atoms and ions in $\R^3$ interacting with the quantized
electromagnetic field. Because of the translation invariance we consider the
reduced hamiltonian associated with the total momentum. After introducing an
ultraviolet cutoff we prove that the reduced hamiltonian for atoms has a ground
state if the coupling constant and the total momentum are sufficiently small.
In the case of ions an extra infrared regularization is needed. We also
consider the case of the hydrogen atom in a constant magnetic field. Finally we
determine the absolutely continuous spectrum of the reduced hamiltonian.