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Single Molecule Spectroscopy (SMS)

Single Molecule Spectroscopy (SMS). 2010/6/9 Miyasaka Lab. Iida Atsushi. Contents. Introduction -History of Single Molecule Spectroscopy (SMS) -Difference between ensemble and single-molecule measurement

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Single Molecule Spectroscopy (SMS)

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  1. Single Molecule Spectroscopy(SMS) 2010/6/9 Miyasaka Lab. Iida Atsushi

  2. Contents • Introduction -History of Single Molecule Spectroscopy (SMS) -Difference between ensemble and single-molecule measurement -Information obtained only by SMS • Measurement -Principle -Single-molecule detection • Confocal Microscope • Wide-Field Mycroscope • Representative results of SMS -Blinking -Spectral jump -Photon antibunching • My work

  3. History of Single Molecule Spectroscopy • 1989 W. E. Moerner et al. First detection of single-molecule with FM spectroscopy • 1990 M. Orrit et al. Fluorescence excitation spectra of single molecules • 1992 T. Basche et al. Blinking, Spectral jump

  4. Difference between ensemble and single-molecule measurements The result of ensemble measurement Ensemble An emission spectrum of a single molecule “Single molecule”

  5. SMS Ensemble measurement Intensity of red light Information obtained only by SMS FRET : 励起エネルギー移動 Direct observation of dynamical state changes The signal is averaged.

  6. Evaluation of nano-scale heterogeneity Energy level Life-time Diffusion Information obtained only by SMS Fluorescent molecule Polymer Properties of a molecule depend on its microscopic environment .

  7. Single fluorescence molecules in dark space can be detected optically. Principle Absorption I0 I0 I I Fluorescence Quitesensitive detector Key : Reduction of the noise from the background

  8. 3-dimentianal resolution Small background High temporal resolution Confocal Microscope Intensity trajectory Life-time Sample Objective lens Coincidence Pinhole Detector

  9. Wide-field Microscope 2-dimentioanl resolution Objective lens ・translational diffusion coefficient High sensitivity camera ・rotational motion ・Many molecules can be observed at a time.

  10. Blinking Dye molecules in a polymer film (PMMA) non-luminescent Each molecule emits light frequently. Non-luminescent process, for example photo-ionization, relates with this phenomena.

  11. Spectral jump Host molecule p-terphenyl Guest molecule pentacene M. Oritt, J. Bernard, Phys. Rev. Lett., 65, 2716 (1990).

  12. Photonantibunching Beam splitter (50:50) Detector 1 A molecule emits one photon from its one excited state. If you detect photons from a single molecule, there is no possibility to detect two photons by the detector 1 and 2 at the same time. Detector 2 Photons can not be divided. Phenomenon that multiple photons do not exist at the same time. 12

  13. 125ns Coincidence Single molecule Ensemble Events Events -125 0 125 Delay /ns -125 0 125 Delay /ns Interphoton arrival time Lightpulse Photon Photodetector 1 Photodetector 2 Photon antibunching The coincidence event is not observed for single molecule system. 13

  14. - - - - - surface area volume My Work - octane water Droplet is very small. specific surface area(比表面積) The surface is anionic. The interaction between surface and a solute depends on the size and the surface charge. Influence of surface is very big in ultrasmall droplet.

  15. My Work Transmission Fluorescence Dye molecule is moving in the droplet, and absorbs to the surface. Only one dye molecule exists in the droplet.

  16. Life-time SDS<Triton x-100 (6.2ns) (3.6ns) My work surfactant ; triton x-100 (non-ionic) SDS (anionic) Triton x-100 The nano-scale environment around a solute is similar to that in the bulk octane. Triton x-100 A solute is diffusing center of the droplet. SDS SDS A solute exists in the different environment from the bulk octane. A solute is diffusing near the surface. Life-time of the dye molecules in bulk octane is 6.4ns.

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