IONIC TRANSITIONS HYPERSENSITIVE TO ENVIRONMENT

It is shown that the so-called dynamic-coupling mechanism of Mason, Peacock and Stewart, which was introduced to account for the peculiar hypersensitivity of the optical transitions of rare-earth ions with respect to their environment, is formally identical to an earlier proposed mechanism based on an inhomogeneous dielectric. Errors in the derivation of the dynamic-coupling mechanism are corrected, and examples of the rare-earth trihalides are considered. © 1979 American Institute of Physics.