20Ne22Ne

20Ne22Ne refers to the isotopic ratio of neon-20 to neon-22, commonly written as 20Ne/22Ne. Neon has three stable isotopes—20Ne, 21Ne, and 22Ne—with 20Ne and 22Ne being the major constituents in many reservoirs. In Earth's atmosphere, the relative abundances yield a 20Ne/22Ne ratio of about 9.8, though natural samples can show deviations from this terrestrial standard due to different nucleosynthetic inputs and planetary processes.

Production and significance: 20Ne and 22Ne originate from stellar nucleosynthesis. 20Ne is produced in massive stars and supernovae through alpha-capture and related processes, while 22Ne is mainly formed during helium burning via reactions starting from 14N, ultimately contributing to the s-process neutron source through 22Ne(α,n)25Mg at higher temperatures. The 20Ne/22Ne ratio thus encodes information about the stellar sources that contributed neon to a given reservoir and about subsequent chemical and physical processing.

Measurement and interpretation: The ratio is determined by isotope ratio mass spectrometry on neon released from samples such as rocks, meteorites, lunar material, or terrestrial gases. Results are typically compared to atmospheric neon as a standard. Variations in 20Ne/22Ne can indicate solar wind implantation, nucleosynthetic admixtures from ancient stellar sources, or degassing and isotopic fractionation processes on planetary bodies.

Applications: The 20Ne/22Ne ratio is used in cosmochemistry and planetary science to study the sources of noble gases, trace the history of solar system formation, and characterize xenon and neon isotope systems in meteorites, lunar samples, and planetary atmospheres. It complements information from other neon isotopes (notably 21Ne) to build a fuller picture of neon’s origin and evolution.