Luminescence of dyes

Abstract Pressure-sensitive paint (PSP) is applied to the areodynamics measurement. PSP is optical sensor based on the luminescence of dye probe molecules quenching by oxygen gas. Many PSPs are composed of probe dye molecules, such as polycyclic aromatic hydrocarbons (pyrene, pyrene derivative etc.), transition metal complexes (ruthenium(II), osumium(II), iridium(III) etc.), and metalloporphyrins (platinum (II), palladium(II), etc.) immobilized in oxygen permeable polymer (silicone, polystyrene, fluorinated polymer, cellulose derivative, etc.) film. Dye probe molecules adsorbed layer based PSPs such as pyrene derivative and porphyrins directly adsorbed onto anodic oxidised aluminium plat substrate also developed. In this section the properties of various oxygen permeable polymer for matrix and various dye probes for PSP are described. 

This conclusion is in agreement with experiments in which a smootb quartz and cellulose were used as substrates. For above materials the transfer of excitation energy of the dye into the substrate is low which is confirmed by intensive luminescence of adsorbed tripaflavine. Note, that the activation energy of emission of singlet oxygen is close for zinc oxide oxidized by oxygen atoms, quartz and cellulose and amounts to 5-10 kcal/mol [83]. 

Rubinov AN, Tomin VI (1971) Bathochromic luminescence of organic dyes in alcohol solutions and polymer matrices. Opt Spectros 32 424-428... 

Fluorescent silica nanoparticles, called FloDots, were created by Yao et al. (2006) by two synthetic routes. Hydrophilic particles were produced using a reverse micro-emulsion process, wherein detergent micelles formed in a water-in-oil system form discrete nanodroplets in which the silica particles are formed. The addition of water-soluble fluorescent dyes resulted in the entrapment of dye molecules in the silica nanoparticle. In an alternative method, dye molecules were entrapped in silica using the Stober process, which typically results in hydrophobic particles. Either process resulted in luminescent particles that then can be surface modified with... 

Dual lifetime referencing (DLR) is another powerful technique that enables referenced measurements in case of fluorescent indicators [23]. In this method, the analyte-dependent signal from an indicator is referenced against the signal from an inert luminophore. This can be realized in both the time domain [24] and in the frequency domain [25]. Often, a luminescent reference dye is embedded into gas blocking nanobeads to avoid oxygen quenching. Polymers with very low gas permeability such as poly(acrylonitrile) [24] or poly(vinylidene chloride-co-acry-lonitrile) [26] are the best choice here. 

The reader is referred to other reviews for detailed discussions of the electronic states and luminescence of nucleic acids and their constituents/0 fluorescence correlation spectroscopy/2) spectroscopy of dye/DNA complexes/0 and ethidium fluorescence assays/4,0 A brief review of early work on DNA dynamics as well as a review of tRNA kinetics and dynamics have also appeared. The diverse and voluminous literature on the use of fluorescence techniques to assay the binding of proteins and antitumor drugs to nucleic acids and on the use of fluorescent DNA/dye complexes in cytometry and cytochemistry lies entirely outside the scope of this chapter. 

Fiber optical sensors are popular devices for the design of optical chemosen-sors. They are based on the change of optical properties (such as adsorption or luminescence) of particular chemical indicators. For example, fiber optical oxygen sensors are produced by the immobilization of oxygen sensitive dyes on the tip of an optical fiber and in an appropriate matrix. 

The fines of Er " " are difficult to point out because they have short decay times, which are comparable with the decay of broad band luminescence of scheelite at the same spectral region. Using a dye laser with 357 nm emission solved this problem. It is effective for Er " " but not suitable for the excitation of the WO4-center (Fig. 4.8c). These fines of Er " " are most clearly seen with a narrower gate width when the luminescence of short-lived centers dominates. Investigation of the time-resolved luminescence of synthetic CaW04 Er confirmed our interpretation (Fig. 5.19). 

Similar behavior is observed in the potential-dependent luminescence of a ruthenium dye adsorbed to 2 [52]. Although the flat-band potential of 2 is known to shift positive in the presence of the potential-determining Li+ ion, relative to the TBA+ ion [5,68], this effect cannot explain the observed behavior. For example, in our experiments, the dye injects in both cases, but it takes a much smaller negative potential excursion to turn off the injection process in the presence of Li+ than with TBA+ [52]. This is the opposite of what would be expected if only equilibrium (i.e., dark) band edge motion were responsible for the effect. 

It remains to be determined to what extent the dye adsorption technique is applicable to other substrates. No evidence was obtained for Pseudocyanine adsorption to Mn02, Fe2Os or to pure silver surfaces, although this dye can be bound to mica, lead halides, and mercury salts with formation of a /-band (61). Not only cyanines but other dye classes can yield surface spectra which may be similarly analyzed. This is specifically the case with the phthalein and azine dyes which were recommended by Fajans and by Kolthoff as adsorption indicators in potentio-metric titrations (15, 30). The techniques described are also convenient for determining rates and heats of adsorption and surface concentrations of dyes they have already found application in studies of luminescence (18) and electrophoresis (68) of silver halides as a function of dye coverage. 

Figure 5.4, one can easily understand why the interfacial electron transfer should take place in the 10-100 fsec range because this ET process should be faster than the photo-luminescence of the dye molecules and energy transfer between the molecules. Recently Zimmermann et al. [58] have employed the 20 fsec laser pulses to study the ET dynamics in the DTB-Pe/TiC>2 system and for comparison, they have also studied the excited-state dynamics of free perylene in toluene solution. Limited by the 20 fsec pulse-duration, from the uncertainty principle, they can only observe the vibrational coherences (i.e., vibrational wave packets) of low-frequency modes (see Figure 5.5). Six significant modes, 275, 360, 420, 460, 500 and 625 cm-1, have been resolved from the Fourier transform spectra of ultrashort pulse measurements. The Fourier transform spectrum has also been compared with the Raman spectrum. A good agreement can be seen (Figure 5.5). For detail of the analysis of the quantum beat, refer to Figures 5.5-5.7 of Zimmermann et al. s paper [58], These modes should play an important role not only in ET dynamics or excited-state dynamics, but also in absorption spectra. Therefore, the steady state absorption spectra of DTB-Pe, both in...

Another completely different approach consists in choosing a dye, that already possesses aminocarboxylate functions (Meshkova et al., 1992a), such as triphenylmethane dyes. The latter can be used for selective luminescent determination of Nd111 and Ybm in samarium oxide, for instance. As previously described in the section devoted to /3-diketonates (section 3.2.1), the triplet excited states of /i-dikctonatcs lie at energies >20 000-25 000 cm-1, above most of the accepting levels of Lnm ions. As a consequence, determination of Ndm and Yb111 in europium or samarium oxides is difficult using /3-dike to nates since these two ions exhibit luminescence in the NIR, especially Smm with emission lines at 908, 930, 950, and 1038 nm close to the analytical lines of Ndm and Ybm. Therefore, the detection limit of Ndm and Ybm in samarium compounds by luminescence of their ternary complexes with tta and phen is only 0.1-1 wt%. 

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