Photophysical processes exploited in digital imaging microscopy: Fluorescence resonance energy transfer and delayed luminescence

The spectroscopic techniques of fluorescence resonance energy transfer and of time-resolved delayed fluorescence and phosphorescence have been introduced into a microscope equipped with a solid-state CCD camera and phase-locked excitation and emission choppers. The distribution and replication of DNA in cells has been quantitated by these methods, as well as by confocal laser scanning microscopy. Sites of replication in living cells can be uniquely identified by delayed luminescence.