Resonance enhanced fluorescence

Pan, S. L., Rothberg, L.J., Nolte, A.J.,Rubner, M. F., Swager, T. M.(2005). Distance dependent investigation of surface plasmon resonance enhanced fluorescent emission using sequentially adsorbed polyelectrolyte mutilayer spacer. Proc. SPIE 5927 592705... 

Phenomena such as quantum dots, fluorescent nano clusters, REF (resonance enhanced fluorescence), SERS (surface enhanced Raman-spectroscopy), SEA (surface enhanced absorption), or unique catalytic effects are the major technological quantum leaps of nano technology. 

The general principle of detection of free radicals is based on the spectroscopy (absorption and emission) and mass spectrometry (ionization) or combination of both. An early review has summarized various techniques to detect small free radicals, particularly diatomic and triatomic species.68 Essentially, the spectroscopy of free radicals provides basic knowledge for the detection of radicals, and the spectroscopy of numerous free radicals has been well characterized (see recent reviews2-4). Two experimental techniques are most popular for spectroscopy studies and thus for detection of radicals laser-induced fluorescence (LIF) and resonance-enhanced multiphoton ionization (REMPI). In the photochemistry studies of free radicals, the intense, tunable and narrow-bandwidth lasers are essential for both the detection (via spectroscopy and photoionization) and the photodissociation of free radicals. 

Okamura, Y. and Watanabe, Y. (2006). Detecting RNA/DNA hybridization using double-labeled donor probes with enhanced fluorescence resonance energy transfer signals. Methods Mol. Biol. 335, 43-56. 

Blair, S. Chen, Y., Resonant enhanced evanescent wave fluorescence biosensing with cylin drical optical cavities, Appl. Opt. 2001, 40, 570 582... 

This section will focus on the stmcture and energetics of chiral molecular complexes studied with Fourier-transform IR (FT-IR), microwave, LIF, hole burning (HB), IR fluorescence dip spectroscopy, resonance-enhanced multiphoton ionization (REMPl Fig. 5), and RET spectroscopy. 

Tunable laser spectroscopic techniques such as laser-induced fluorescence (LIF) or resonantly enhanced multi-photon ionization (REMPI) are well-established mature fields in gas-phase spectroscopy and dynamics, and their application to gas-surface dynamics parallels their use elsewhere. The advantage of these techniques is that they can provide exceedingly sensitive detection, perhaps more so than mass spectrometers. In addition, they are detectors of individual quantum states and hence can measure nascent internal state population distributions produced via the gas-surface dynamics. The disadvantage of these techniques is that they are not completely general. Only some interesting molecules have spectroscopy amenable to be detected sensitively in this fashion, e.g., H2, N2, NO, CO, etc. Other interesting molecules, e.g. 02, CH4, etc., do not have suitable spectroscopy. However, when applicable, the laser spectroscopic techniques are very powerful. 

In addition to the IR, Raman and LIBS methods previously discussed, a number of other laser-based methods for explosives detection have been developed over the years. The following section briefly describes the ultraviolet and visible (UV/vis) absorption spectra of EM and discusses the techniques of laser desorption (LD), PF with detection through resonance-enhanced multiphoton ionization (REMPI) or laser-induced fluorescence (LIF), photoacoustic spectroscopy (PAS), variations on the light ranging and detecting (LIDAR) method, and photoluminescence. Table 2 summarizes the LODs of several explosive-related compounds (ERC) and EM obtained by the techniques described in this section. 

Two techniques, which appear well suited to the diagnostic probing of practical flames with good spatial and temporal resolution, are coherent anti-Stokes Raman spectroscopy (CARS) and saturated laser fluorescence. The two techniques are complementary in regard to their measurement capabilities. CARS appears most appropriate for thermometry and major species concentration measurements, saturated laser fluorescence to trace radical concentrations. With electronic resonant enhancement (6), CARS may be potentially useful for the latter as well. Fluorescence thermometry is also possible (7, 8) but generally, is more tedious to use than CARS. In this paper, recent research investi-... 

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