38Ar

38Ar, or argon-38, is a stable isotope of the element argon. It has a mass number of 38, with 18 protons and 20 neutrons. It is one of the three stable isotopes of argon, the others being 36Ar and 40Ar. The nucleus has zero nuclear spin and positive parity, reflecting its even numbers of protons and neutrons.

Natural occurrence: 38Ar is a minor component of natural argon, with an isotopic abundance of about 0.06%. It occurs in Earth's atmosphere and in argon-containing minerals, inherited from primordial argon with some cosmogenic production. The most abundant argon isotope in nature is 40Ar, largely produced by the radiogenic decay of 40K.

Applications and properties: As a stable, non-radioactive isotope, 38Ar does not decay and is not used for radiometric dating. It is detected and quantified in high-precision mass spectrometry to determine isotopic compositions and to calibrate measurement systems in geochemistry and atmospheric science. Due to its rarity, 38Ar has limited commercial uses, but it contributes to detailed isotopic studies of argon in rocks, minerals, and atmospheric samples.