Thomas Chen, Juerg Froehlich, Alessandro Pizzo Infraparticle Scattering States in Non-Relativistic QED: II. Mass Shell Properties (594K, AMS Latex) ABSTRACT. We study the infrared problem in the usual model of QED with non-relativistic matter. We prove spectral and regularity properties characterizing the mass shell of an electron and one-electron infraparticle states of this model. Our results are crucial for the construction of infraparticle scattering states, which are treated in a separate paper.