Trapped-valence model, intervalence

This ion provides a model for study of intervalence transfer absorption bands characteristic of trapped valence species that correspond to the process... 

Piepho has treated intervalence transitions using a relatively simple three-center molecular orbital model in which vibronic coupling is introduced as a pseudo-Jahn-Teller perturbation. This could be a valuable approach, and it can probably be generalized to a great variety of problems. In this report, Piepho uses the approach to calculate intervalence transition band shapes for a range of vibronic couplings, and she discusses the vibronic criteria for valence trapped and delocalized systems. 

Katriel and Ratner ° have developed a simple model to describe the effects of selective solvation on intervalence absorption spectra (e.g., see Ref. 102). Lewis and Obeng have reported that the ionic-strength-dependent intervalence absorption maximum ( op) is also dependent on the reduction potential of the cationic oxidant. This observation is attributed to an effect of ionic aggregation. Jozefiak et have reported infrared evidence that mixed valence, conjugated semiquinones, prepared electrochemically in DMF, are valence trapped. 

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