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Provisional Recommendations

Inorganic Chemistry Division
Commission on Nomenclature of Inorganic Chemistry

Names for Muonium Atoms and Ions

Although chemical reactions of muonium atoms have been studied for more than two decades, the nomenclature of muonium and related species has not been addressed by IUPAC. The name 'muon' is used in physics for the species that belong to the lepton family and that are designated with the symbols m+ and m-, each having a mass 207 times that of the electron. When a negative muon replaces an electron in the 1s orbital of an atom, then this atom is called a 'muonic' atom: H+m- is 'muonic hydrogen'. Replacement of an electron by a muon in other atoms is possible. Negative muons have been less well studied than positive muons, which are formed as energetic, polarized beams at specialized facilities. The positive muon can abstract an electron near the end of the radiation track, and the combination of positive muon and electron mimics the reactivity of the hydrogen atom. For this combination, the name 'muonium' has been used. Were a negative muon to replace an electron in muonium, the name would be 'muonic muonium' ( m+m-).

> Download full text of the Provisional Recommendations (pdf file - 15 KB)

Comments by 31 December 2000
To Prof. Dr. W. H. Koppenol
Laboratorium f�r Anorganische Chemie
Eidgen�ssische Technische Hochschule
Universit�tsstrasse 6
CH-8092 Z�rich, Switzerland

Tel.: +41-1-632-2875
Fax: +41-1-632-1090
E-mail: [email protected]

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