title: Two-channel sequential single-molecule measurement.
abstract: Experimental results are given which demonstrate the sequential detection of single molecules with a measurement efficiency of near unity. IR140 dye molecules are detected in sequential probe volumes within a flowing stream through a 9 μm i.d. capillary. The measurement of single molecules was confirmed by means of autocorrelation, photobleaching, visual observation, and cross-correlation analysis. The number of single molecules photobleached prior to being measured in the second probe region was in excellent agreement with the bulk studies described by a photodestruction curve. A cross-correlation peak with a temporal delay corresponding to the interprobe volume transit time and a width in agreement with parabolic flow give a clear indication of sequential detection. The near unity measurement efficiencies for both channels indicates the great potential for rapid quantitative analysis of dilute solutions.
authors.affiliation: Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200.
authors.forename: R D
authors.initials: RD
authors.lastname: Guenard
authors.forename: L A
authors.initials: LA
authors.lastname: King
authors.forename: B W
authors.initials: BW
authors.lastname: Smith
authors.forename: J D
authors.initials: JD
authors.lastname: Winefordner