Detection of single fluorescent molecules in microdroplets: Experiment and photophysics
- Oak Ridge National Lab., TN (United States)
Several laboratories around the world are now working on experiments to detect single molecules. Many elegant experiments have been performed on single molecules in host crystals at liquid helium temperatures, and more recently near field optical microscopy experiments have probed single molecules on surfaces. Single molecules in liquids have been probed directly or indirectly through an amplification process. All of these studies have used fluorescence as the technique for observing the molecule. The most challenging of all these experiments is the direct detection of a single molecule in solution. Finite photochemical lifetimes limit the fluorescence signal from a single molecule. This limitation necessitates extremely small probe volumes ({approx}1 pL) for detection. Our laboratory has chosen to use microdroplets with diameters of approximately 10 {mu}m or less. Early experiments on, levitated droplets have allowed detection of single R6G molecules in 10-{mu}m diameter droplets of glycerol with a signal-to-noise ratio of 50. More recent experiments in droplet streams have yielded single molecule detection results with a signal-to-noise ratio near 10. These results were obtained with analysis rates of {approx}2 Hz but higher rates are feasible. The microdroplet format also allows the observation of cavity QED enhanced spontaneous emission rates and through solvent mediated effects, enhancements in fluorescence yields. Thus the possibility of increased detection sensitivity in the microdroplet format is promising.
- OSTI ID:
- 560404
- Report Number(s):
- CONF-970443-; TRN: 97:005895-0293
- Resource Relation:
- Conference: 213. national meeting of the American Chemical Society, San Francisco, CA (United States), 13-17 Apr 1997; Other Information: PBD: 1997; Related Information: Is Part Of 213th ACS national meeting; PB: 2904 p.
- Country of Publication:
- United States
- Language:
- English
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