Newtonian Kinetic Isotope Effects. Observation, Prediction, and Origin of Heavy-Atom Dynamic Isotope Effects

摘要

Newton's second law of motion provides that lighter masses accelerate more in response to a constant force. This effect is routinely used to separate isotopes, for example in mass spectrom-etry, but the fractionation of isotopes associated with chemical reactivity originates mainly in quantum effects such as zero-point energy (ZPE) and tunneling. We describe here the observation of unusual heavy-atom kinetic isotope effects (KIEs) in a familiar reaction, an approach to the difficult problem of quantitatively predicting these KIEs, and a discussion of their apparent origin in classical mechanics.