A generalization of the Jablonski diagram to account for polarization and anisotropy effects in time-resolved experiments

Abstract

The Jablonski diagram describes the kinetics of electronic transitions of organic dyes by a rate constant model. A generalization of the Jablonski diagram is presented which allows one to account for polarization and anisotropy effects. To do this, the discontinuous distribution approach (DDA), which models rotational diffusion by discontinuous jumps of the molecule between the principal molecular orientations, is employed. Thus, both rotational diffusion and population dynamics can be modeled by a system of rate differential equations rather than by solving the equation of rotational diffusion, which considerable simplifies the numerics. The generalized Jablonski diagram fully describes the kinetics of any desired electronic and orientational relaxation processes. In particular, orientational relaxation can be calculated for an arbitrary initial distribution of excited molecules. Thus, the new model is especially suited for applications in non-linear spectroscopy since it is not restricted to the small signal limit as many other approaches are.