14c12c ratio carbon dating
1990, without a decay correction Fractionation: The change in isotopic ratio that can occur when a material undergoes a chemical reaction or certain types of physical processes.
Radiocarbon ages are inferred from the measurements subject to a number of assumptions and qualifications. Cosmic Ray: The high energy atomic radiation that bombards the earth from space.
Chemical reactions are not the only causes of fractionation.
Evaporation, condensation, diffusion or the passage of vapour through a small aperture can also give rise to isotopic fractionation.
Atmospheric CO2 has a d13C of about -7o/oo whereas the d 13C of wood is about -25o/oo.
The chain of chemical reactions leading to the formation of cellulose has resulted in the cellulose being depleted in 13C relative to the CO2.