Iridium193

Iridium193 is a naturally occurring isotope of the chemical element iridium, one of the platinum group metals. It possesses 77 protons and 116 neutrons, giving it an atomic mass of 192.9618 atomic mass units. The isotope has a half‑life of 77 years, and it decays primarily via beta minus emission to form ruthenium193. This decay mode results in a gradual buildup of the more stable ruthenium193 within natural iridium deposits over geological timescales.

In natural iridium ore, Ir193 constitutes roughly 90 % of the elemental iridium present, with Ir192 making up the remaining 10 %. This distribution differs from many other transuranic and fission products, which tend to appear in much smaller fractions. The relatively long half‑life and abundance make Ir193 a useful tracer in geological studies, providing insight into the differentiation and tectonic history of the Earth's mantle.

The isotope is produced artificially in nuclear reactors and particle accelerators by irradiation of iridium metal. High‑purity samples of Ir193 are essential for calibrating analytical instrumentation, such as inductively coupled plasma mass spectrometry, because of the need for precise mass standards. In addition, Ir193 is used as a source of beta radiation in medical dosimetry, although its application is limited by its longer half‑life and the availability of more convenient isotope alternatives.

Iridium in general is notable for its high density, excellent corrosion resistance and catalytic properties; Ir193 itself shares these chemical traits. Its nuclear properties, however, are less emphasized in industrial applications given the element’s relatively low natural abundance. The isotope nonetheless plays a role in scientific research, particularly in fields such as nuclear physics, geochemistry and materials science.

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