Exotic atom
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An exotic atom is an otherwise normal atom in which one or more sub-atomic particles have been replaced by other particles of the same charge. For example, electrons may be replaced by other negatively charged particles such as muons (muonic atoms) or pions (pionic atoms).[1][2] Because these substitute particles are usually unstable, exotic atoms typically have very short lifetimes and no exotic atom observed so far can persist under normal conditions.
Muonic atoms
In a muonic atom (previously called a mu-mesic atom, now known to be a misnomer as muons are not
Since a muon is more massive than an electron, the Bohr orbits are closer to the nucleus in a muonic atom than in an ordinary atom, and corrections due to quantum electrodynamics are more important. Study of muonic atoms' energy levels as well as transition rates from excited states to the ground state therefore provide experimental tests of quantum electrodynamics.
Muon-catalyzed fusion is a technical application of muonic atoms.
Muonic hydrogen
Muonic hydrogen is like normal hydrogen with the electron replaced by a negative muon—that is a proton orbited by a muon. It is important in addressing the proton radius puzzle.
Muonic helium (Hydrogen-4.1)
The symbol 4.1H (Hydrogen-4.1) has been used to describe the exotic atom muonic helium (4He-μ), which is like
Hadronic atoms
A hadronic atom is an atom in which one or more of the orbital electrons are replaced by a negatively charged hadron.[8] Possible hadrons include mesons such as the pion or kaon, yielding a pionic atom[9] or a kaonic atom (see Kaonic hydrogen), collectively called mesonic atoms; antiprotons, yielding an antiprotonic atom; and the
Σ−
particle, yielding a
Σ−
or sigmaonic atom.[10][11][12]
Unlike leptons, hadrons can interact via the
Onium
An onium (plural: onia) is the bound state of a particle and its antiparticle. The classic onium is
The true analogs of positronium in the theory of strong interactions, however, are not exotic atoms but certain
Muonium, despite its name, is not an onium containing a muon and an antimuon, because IUPAC assigned that name to the system of an antimuon bound with an electron. However, the production of a muon–antimuon bound state, which is an onium (called true muonium), has been theorized.[15]
Hypernuclear atoms
Atoms may be composed of electrons orbiting a hypernucleus that includes strange particles called hyperons. Such hypernuclear atoms are generally studied for their nuclear behaviour, falling into the realm of nuclear physics rather than atomic physics.
Quasiparticle atoms
In
Exotic molecules
An exotic molecule contains one or more exotic atoms.
- Di-positronium, two bound positronium atoms
- Positronium hydride, a positronium atom bound to a hydrogen atom
"Exotic molecule" can also refer to a molecule having some other uncommon property such as a pyramidal hexamethylbenzene#Dication and a Rydberg atom.
See also
References
- ISBN 3-11-013990-1.
- ^ a b Exotic atoms Archived 2007-12-22 at the Wayback Machine, AccessScience, McGraw-Hill. accessdate=September 26, 2007.
- ^ Dr. Richard Feynman's Douglas Robb Memorial Lectures
- ^ a b
Fleming, D. G.; Arseneau, D. J.; Sukhorukov, O.; Brewer, J. H.; Mielke, S. L.; Schatz, G. C.; Garrett, B. C.; Peterson, K. A.; Truhlar, D. G. (28 Jan 2011). "Kinetic Isotope Effects for the Reactions of Muonic Helium and Muonium with H2". Science. 331 (6016): 448–450. S2CID 206530683.
- ^ Moncada, F.; Cruz, D.; Reyes, A (2012). "Muonic alchemy: Transmuting elements with the inclusion of negative muons". Chemical Physics Letters. 539: 209–221. .
- ^ Moncada, F.; Cruz, D.; Reyes, A. (10 May 2013). "Electronic properties of atoms and molecules containing one and two negative muons". Chemical Physics Letters. 570: 16–21. .
- ISBN 978-1-4684-8345-1.
- ISBN 981-238-371-9.
- S2CID 218527999.
- ^ p. 8, §16.4, §16.5, Deloff.
- ^ a b The strange world of the exotic atom, Roger Barrett, Daphne Jackson and Habatwa Mweene, New Scientist, August 4, 1990. accessdate=September 26, 2007.
- ISBN 81-203-1007-1.
- ^ Exotic atoms cast light on fundamental questions, CERN Courier, November 1, 2006. accessdate=September 26, 2007.
- S2CID 1165868.
- ^ DOE/SLAC National Accelerator Laboratory (June 4, 2009). "Theorists Reveal Path To True Muonium – Never-seen Atom". ScienceDaily. Retrieved June 7, 2009.