The first example was discovered by Robert N. Clayton, Toshiko Mayeda, and Lawrence Grossman in 1973,[2] in the oxygen isotopic composition of refractory calcium–aluminium-rich inclusions in the Allende meteorite.
The inclusions, thought to be among the oldest solid materials in the Solar System, show a pattern of low 18O/16O and 17O/16O relative to samples from the Earth and Moon.
Originally this was interpreted as evidence of incomplete mixing of 16O-rich material (created and distributed by a large star in a supernova) into the Solar nebula.
Large, 1:1 enrichments of 18O/16O and 17O/16O in ozone were discovered in laboratory synthesis experiments by Mark Thiemens and John Heidenreich in 1983,[3] and later found in stratospheric air samples measured by Konrad Mauersberger.
[5] Theoretical calculations[6] by Rudolph Marcus and others suggest that the enrichments are the result of a combination of mass-dependent and mass-independent kinetic isotope effects (KIE) involving the excited state O3* intermediate related to some unusual symmetry properties.