Linewidth behavior of the ESR signal of dye radicals on spectrally sensitized AgX microcrystals
Faculty of Sciences. Physics
Engineering sciences. Technology
IS&T 50TH ANNUAL CONFERENCE, FINAL PROGRAM AND PROCEEDINGS
50th Annual Meeting of the Society-of-Imaging-Science-and-Technology, MAY 18-23, 1997, CAMBRIDGE, MA
, p. 121-124
University of Antwerp
The authors earlier introduced two models to describe the formation and decay kinetics of dye radicals in a quantitative way, measured with Electron Spin Resonance (ESR) spectroscopy.(1) One model is based on an equilibrium between dye molecules and dye radicals, the other on an equilibrium between dye molecules, dye radicals and doubly oxidized dye molecules. The models are able to fit and predict the experimental data. The most important new element in one of the models is the possibility of having a double oxidation of a dye molecule during intrinsic irradiation. In the case of a system where double oxidation is observed, some dyes are found to possess a peculiar behavior of linewidth versus signal amplitude. The linewidth of the signal not only depends on the concentration of the dye radicals, but also on the relative concentration of the molecular and doubly oxidized state. This observation can be explained using the fact that there exist different mechanisms which influence the linewidth. Spin-spin interaction and charge transfer between a molecule and its cation in the vicinity are used to explain the experimental results.