The Mösbauer effect [l] is the recoil-free emission and absorption of low-energy gamma rays by the nuclei of atoms in solids. Unlike the “free” atom so commonly employed in theoretical considerations, the atom in a solid possesses some unique properties not experienced by the “free” atom. The splitting of atomic energy levels by the crystal field surrounding an atom in a solid is one example. The Mössbauer effect is another which makes Mösbauer spectroscopy a powerful method for the study of the properties of solids and, by logical extension, the properties of solid surfaces.