Amplified fluorescence quenching

AMPLIFIED FLUORESCENCE QUENCHING AND EFFICIENT ENERGY TRANSFER IN LB FILMS... 

We have shown that redox chromophores organized in LB films with resped to their orientation, alignment, or electronic interactions make very useful and specific photoresponses such as amplified fluorescence quenching, photocurrents controlled at the molecular level, photoinduced anisotropic eledrochromism, and photochemically modulated second harmonic generation. These results may contribute to facilitate the design and construction of novel photonic devices in the near future. 

DiCesare N, Pinto MR, Schanze KS, Lakowicz JR (2002) Saccharide detection based on the amplified fluorescence quenching of a water-soluble poly(phenylene ethynylene) by a boronic acid functionalized benzyl viologen derivative. Langmuir 18 7785-7787... 

The fluorescence quenching of Pe and derivatives has been investigated by fluorescence upconversion. Excitation was performed with the frequency-doubled output of a Ti Sapphire amplifier. The instrument response time was around 240 fs with 0.4 mm thick samples. The data were analysed by iterative reconvolution of the instrument response function with trial functions. For most samples, measurements were carried out at three different wavelengths (438, 475, and 490 nm). Global fits were done with all the available data. 

M. laGrone, C. Cumming, M. Fisher, M. Fox, S. Jacob, D. Reust, M. Rockley and E. Towers, Detection of landmines by amplified fluorescence quenching of polymer films A man portable chemical sniffer for detection of ultratrace concentrations of explosives emanating from landmines, Proc. SPIE, Detection and Remediation Technologies for Mines and Minelike Targets V, 4038 (2000) 553-562. 

From these expressions, it becomes clear that operating the chemosensing CP film near its lasing threshold will yield enhancements in fluorescence quenching, thereby enhancing sensitivity. Inspection of Fig. 5.9 shows that optimal sensitivity, at practical pump powers, is obtained when the pump power of the CP is at the onset of amplified stimulated emission (ASE), for the exposed film. Practical implementation of the concept would require rastering of the incident power intensity to locate the pump power that yields the maximum signal response. 

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