DETECTION OF SINGLE RHODAMINE-6G MOLECULES IN LEVITATED MICRODROPLETS

Single Rhodamine 6G (R6G) molecules in levitated glycerol microdroplet s have been detected with signal-to-noise ratios of >40 using CW laser -induced fluorescence. The fluorescence signal from single R6G molecul es was identified by the magnitude of the fluorescence signal and by t he unique time dependence of the fluorescence count rate before photob leaching. This high sensitivity allows single molecules to be counted by use of a digital detection approach offering significantly lower de tection limits than those possible with conventional detection methods .