Single molecule fluorescence techniques spectroscopy

Finally, in Chapter 11 some advanced techniques are briefly described fluorescence up-conversion, fluorescence microscopy (confocal excitation, two-photon excitation, near-field optics, fluorescence lifetime imaging), fluorescence correlation spectroscopy, and single-molecule fluorescence spectroscopy. 

SECM instruments (77,78) will undoubtedly increase the scope and power of SECM. Further improvements in the power and scope of SECM has resulted from its coupling scanning probe or optical imaging techniques, such as AFM (57,79) or single-molecule fluorescence spectroscopy (80). The combined SECM-AFM technique offers simultaneous topographic and electrochemical imaging in connection to a probe containing a force sensor and an electrode component, respectively. 

Nanoporous platforms recently have found utility in the fields of plasmonics and optical detection. Nanoporous gold fllms and metallic-coated nanopores - have been applied to techniques like surface-plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS). Additionally, nanoporous metal has been demonstrated to enhance single-molecule fluorescence intensity of immobilized fluorophores due to the enhanced localized plasmon field present within the nanopores. Optically transparent alumina membranes have been developed and found utility as optical biosensors. Additionally, nanoporous gold has been demonstrated to optically detect Hg + ions at concentrations smaller than parts per trillion. A fiber-optic ultrasound generator has been developed from the excitation of gold nanopores with a nanosecond laser. ... 

It should also be recalled that in the last few years the concept of molecules as nanoscale objects with their own shape, size and properties has been confirmed by new, very powerful techniques, such as single-molecule fluorescence spectroscopy and the various types of probe microscopy, capable of seeing [22] or manipulating [23] single molecules. It has been possible, for example, to make ordered arrays of molecules (e.g. to write words [24] and numbers [25] by aligning... 

Johan Hofkens received his MSc and PhD degrees in chemistry from the University of Leuven (KULeuven). After postdoctoral research with Prof Masuhara at Osaka University and Prof Barbara at the University of Minneapolis, he rejoined the KULeuven, starting and supervising the Single Molecule Unit in the group of Prof De Schiyver. In 2005, he was appointed as Research Professor at the KULeuven and recently he was promoted to full professor. His research interests are fast spectroscopy, (single molecule) fluorescence microscopy, Raman spectroscopy and plasmonics, and the application of these techniques in material science (with an emphasis on polymers) and biosciences. 

Optical properties of dendrimers bearing eight chromophores have been examined by single molecule spectroscopy techniques. It is especially exciting that variations in the spectra are recorded if one of these dendrimers is observed for a period of time under continuous irradiation.1481 The fluorescence intensity of the dendrimer nanoparticle also jumps between discrete emissive levels. All these findings suggest the existence of strong electronic interactions between several perylene imide chromophores within one dendrimer and provide new... 

Reading the electronic state of the switch is often performed by use of optical transient absorption and fluorescence emission spectroscopy. Fluorescence is a much more sensitive technique, and can be done even at the single molecule level. 

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