The fractionation technique dating
Atoms of larger or smaller mass may be favored in such a situation.
A radiocarbon measurement, termed a conventional radiocarbon age (or CRA) is obtained using a set of parameters outlined by Stuiver and Polach (1977), in the journal Radiocarbon.
Isotopic fractionation of stable carbon isotopes Carbon-13 (13C) and Carbon-12 (12C) involves alterations in the ratios of isotopic species as a function of their atomic mass as a result of natural biochemical processes.
Variations as such are unrelated to time and natural radioactive decay.
This value is not reported but it is used to produce the correct “Conventional Radiocarbon Age”.
Important: Reporting conventions using “Conventional Radiocarbon Age” terminology indicate the result has been corrected for isotopic fractionation.– Beta also measures a second δ13C value in an isotope ratio mass spectrometer (IRMS δ13C).