isotope effect

Also contains definition of: equilibrium isotope effect
The effect on the rate or @[email protected] of two reactions that differ only in the isotopic composition of one or more of their otherwise chemically identical components is referred to as a @[email protected] or a @[email protected] (or equilibrium) isotope effect, respectively.
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1130 [Terms] [Paper]
PAC, 1994, 66, 2513. (Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)) on page 2521 [Terms] [Paper]
See also:
PAC, 1996, 68, 149. (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 170 [Terms] [Paper]