Exotic atoms

Any negatively charged particle in the Coulomb field of a nucleus forms a Bohr atom. The atom size is inversely proportional to the mass of the particle while the energy is proportional to its mass. In orbits with small overlap with the central nucleus, all the ordinary atomic phenomena are displayed with unusual scale. In such orbits the atom can be used to test quantum electrodynamics and to measure masses, magnetic moments etc. of the elementary particle. In orbits of sizable overlap with the central nucleus the exotic atom becomes an important tool for measuring nuclear charge and current distributions or, for strongly interacting particles, the interacting strength of these with nuclei and the nuclear matter distribution.