Determination of a Purely Electronic Transition in Molecular Electronic Spectra with Screening the Transitions

Abstract

Determination of pure electronic transition (Е₀₀) for molecular electronic spectra by quantum fluctuation theorem (QFT) is considered under external perturbations, decreasing elementary transition intensity and acting as its screening. To consider this effect “screening coefficient” is introduced into the main QFT relation. Using examples of molecular electronic spectra from the visible, UV, and X-ray regions, it is shown that the introduction of a screening coefficient brings the spectrum into conformity with QFT conditions and, consequently, with the conditions for determining a pure electronic transition using them. It means the reduction of the external excitation energy to the value suitable for QFT due to the screening. The operation of QFT model in molecular electronic UV-Vis and x-ray spectra is given. In proposed model Е₀₀ depends on screening coefficient, but Е₀₀ quantity, which is the closest to the true one, corresponds to the lowest screening coefficient.