Strategy for room temperature spectroscopy of single molecules

Laser-induced fluorescence (LIF) from single molecules at room temperature displays rich dynamics of reversible and irreversible transitions within the photodestruction lifetime of the molecule. In contrast to ensemble studies, these transitions are directly resolved when the fluorescence signal is monitored in time. We present a strategy and describe the instrumentation needed for spectroscopic studies on a large number of individual molecules. It is based on a computer controlled optical system which automatically and rapidly positions single molecules in the excitation volume of a confocal microscope and subsequently performs spectroscopic measurements. Examples for such spectroscopies are presented.