A dark-field method for measuring absorption cross sections of single molecules

A method for measuring absorption cross sections of single molecules by the intensity of resonance Rayleigh light scattering using a dark-field confocal microscope is proposed. It is shown by using a conjugated polymer as an example that this method can be used to study multichromophore molecules at room temperature. The method proposed makes it possible to apply single-molecule spectroscopy to weakly fluorescing molecules, investigate the distribution of molecules over the fluorescence quantum yield and the mechanisms of photodestruction, and to obtain data on the nature of intermittent fluorescence of multichromophore objects.