 Equilibrium fractionation

Equilibrium fractionation is a process that occurs during the partitioning of isotopes between two phases (such as liquid and gas or solid and liquid) at thermal equilibrium. It is based on the principle that isotopes of a given element, although chemically identical, have slightly different physical properties due to their differing masses. During equilibrium fractionation, the distribution of isotopes between the two phases changes such that the heavier isotopes tend to concentrate in one phase while the lighter isotopes concentrate in the other.