Anisotropy shape control via light quenching and ground state depletion

Abstract

The influence of light quenching (LQ) and ground state depletion on the shape of the angular distribution of the transition dipole moments of molecules in the first excited singlet state is calculated theoretically. The theoretical results are tested experimentally using fluorescein and DCM as fluorophores. Both effects were shown to occur under `normal' experimental conditions in ps-laser experiments. The initial fluorescence anisotropy can be reduced down to zero under ground state depletion or LQ. It is also shown that, using appropriate conditions the initial anisotropy can be increased up to values larger than could be achieved even with two photon absorption.