Elementary optical transitions of electron and proton

Author: lasha laliashvili
Keywords: electron, proton
Annotation:

The firs theoretical attempts towards the mechanistic understanding of simplest optical electron or proton transitions within the irregular condensed-phase environment (such as aqueous solutions, viscous and ultra-viscous liquids, biomolecular systems, etc.) were made by Hush, Dogonadze, Marcus and other researchers nearly five decades ago. These endeavors immediately followed the preceding spectacular theoretical developments on the intrinsic physical mechanisms for a multitude of thermally –induced (activated) charge-transfer processes, supported by rather successful first series of experimental testing. Theoretical analysis indicated that, in general, any elementary thermal process should have its optical counter-part. However, this correspondence is not full because the numerical set of optical processes, in overall, is greatly exceeds that of thermal transitions. Indeed, the former ones count both, the inner-sphere and outer-sphere orbital transitions, whereas the latter normally cover solely the outer-sphere orbital transition (however, note the existence of intermediate cases as well). The most strict physical boundary is set by the actuality that the occurrence of a thermal process necessitates the interception of respective initial and final energy terms, whereas the occurrence of an optical one – does not. For this reason, the elementary inner-orbital optical transitions have no thermal analogs. As a matter of fact, both, the inner-orbita and outer-orbital optical charge transitions can be considered in the framework of the generalized Mulliken-Hush-Newton theoretical approach. As to the experimental verification of outer-orbital optical transitions, in contrast to their inter-orbital analogs (which are familiar to us as a multitude of “colorful” manifestations of very familiar, thermally “stable” molecular assemblies), their disclosure and scrutiny came out to be a difficult task. In the framework of the present seminar talk (the PhD student’s educational component) will be presented and discussed a few of accessible examples of respective experimental reports.