A Modified Phase-Modulation Spectrofluorometer for Lifetime-Resolved Fluorescence-Detected Circular Dichroism

Abstract

The first demonstration of lifetime resolution in fluorescence-detected circular dichroism (FDCD) is described, performed on a modified phase-modulation spectrofluorometer in which a Babinet-Soleil compensator is used to generate the circularly polarized excitation. Measurements of optically inactive solutions indicate the absence of significant instrumental or optical artifacts for steady-state and lifetime-resolved FDCD. Advantages of the instrumental approach are discussed and early results are presented for a system of benzo(a)pyrene and benzo(k)fluoranthene in γ-cyclodextrin, demonstrating the accuracy of the lifetime determinations with circularly polarized excitation as well as the applicability of lifetime-resolved FDCD for studies of induced chirality in asymmetric microenvironments.