Term: method of isotopic perturbation
https://doi.org/10.1351/goldbook.M03880

Definition:
NMR shift difference measurement of the isotope effect on a fast (degenerate) equilibrium between two species which are equivalent except for isotopic substitution. This can be used to distinguish a rapidly equilibrating mixture with time-averaged symmetry from a single structure with higher symmetry.

Related Terms:
1) isotope effect (http://doi.org/10.1351/goldbook.I03327).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1132 (https://doi.org/10.1351/pac199466051077)

Citation: 'method of isotopic perturbation' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.M03880

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