Top 10 Key Players companies in Isotopes of carbon
by Most Patent Filings in the Japan in 2019

Carbon (₆C) has 15 known isotopes, from ⁸C to ²²C, of which ¹²C and ¹³C are stable. The longest-lived radioisotope is ¹⁴C, with a half-life of 5,700 years. This is also the only carbon radioisotope found in nature—trace quantities are formed cosmogenically by the reaction ¹⁴N + ¹n → ¹⁴C + ¹H. The most stable artificial radioisotope is ¹¹C, which has a half-life of 20.334 minutes. All other radioisotopes have half-lives under 20 seconds, most less than 200 milliseconds. The least stable isotope is ⁸C, with a half-life of 2.0 x 10⁻²¹ s.