  We consider a system consisting of an atom in the dipole approximation,
coupled to the electromagnetic field. Using recently introduced renormalized
coordinates and dressed states, we give a non-perturbative solution to the atom
radiation process. From this formalism a non-exponential decay law naturally
emerges. However, at least for low frequencies and weak coupling, there is only
a very small, practically non-detectable, deviation from a purely exponential
decay, in agreement with all previous results in the literature.
