Polarized triplet-minus-singlet absorbance difference spectra measured by absorbance-detected magnetic resonance. An application to photosynthetic reaction centres

Abstract

A method is presented to measure linear dichroic triplet-minus-singlet absorbance difference spectra using absorbance-detected magnetic resonance of the triplet state in zero magnetic field. Orientational selection is achieved by using a linearly-polarised microwave field. The microwave-induced change in the absorbance of light with the electric vector parallel or perpendicular to the microwave field vector is monitored using a Morvue photoelastic modulator and an analyzing polarizer. The method is applied to reaction centres of the photosynthetic bacterium Rhodopseudomonas viridis. © 1984.