ENERGY-TRANSFER INVESTIGATIONS ON PURE CR(III)-COMPLEX COMPOUNDS USING RESONANT EMISSION MEASUREMENTS

Time resolved emission spectra of Cr(III) pentammine complexes excited at resonance conditions are recorded yielding different lifetimes for zero-phonon and vibronic transitions from B-2(1)(C-4 upsilon) The dec ay of zero-phonon transitions furthermore depends on the excitation fr equency. The energy dependence is rationalized assuming a model which describes energy transfer rates between electronic levels of molecules on equivalent sites which compete with intramolecular rates for the d ecay into the ground states. Corresponding rate equations worked out f or some special cases are shown to have analytical solutions. For a co ntinuous set of excited levels, a differential equation is obtained wh ich is known from diffusion or transport phenomena but contain the ene rgy as variable. Simulation of the experiments leads to transfer rate parameters k(d) which are 1 (or 2) orders of magnitude larger than the decay rate k(0). (C) 1997 American Institute of Physics.