Theory of polarized fluorescence and absorption in molecular complexes comprising two chromophores with non-parallel absorption and emission transition dipole moments

This work concerns theoretical determination of the degree of fluorescence polarization and absorption anisotropy in double-chromophore complexes with non-parallel absorption and emission transition dipole moments. Specially, the theory addresses the case in which energy may incoherently transfer within each complex between chromophores with broad and overlapped spectra. Inside each complex the chromophores are rigidly positioned and oriented relative to each other, whilst the complexes themselves are randomly distributed and oriented in space. The cases of steady-state and of δ-pulse excitation are both considered. In general the results obtained apply not only to the specifically considered case of energy migration but more widely, for example to systems exhibiting fast trans-cis isomerization, electron or proton transfer, etc., either alone or in conjunction with conventional energy transfer.