Abstract
A new approach to time-resolved fluorescence spectroscopy based on stimulated emission depletion (STED) of two-photon excited states is presented. Combined with time-resolved detection, STED can circumvent orientational averaging constraints and spontaneous emission selection rules inherent in all conventional techniques. Applications of STED to the study of molecular probe dynamics are presented, together with studies of STED dynamics in a new push-push two-photon chromophore.