exotic atom


exotic atom

[ik¦säd·ik ′ad·əm] (atomic physics) A system in which either the proton that forms the nucleus of a hydrogen atom is replaced by another particle (such as a muon, to form muonium, or a positron, to form positronium), one electron in an ordinary atom is replaced by another particle (such as a muon, pion, or antiproton), or both substitutions are made (as in antihydrogen).