Fluorescence with water vapor

The pressurized hydrolysis technology is available for all TP bumpers of Toyota cars, which are painted with acrylic-melamine resin or alkyd-melamine resin. However, the recovered bumpers contain some repaired ones which are repainted with urethane paint film. The pressurized hydrolysis technology is not available for the urethane paint film because this film is not hydrolyzable with water vapor in such conditions. To maintain the high performance of the recycled material, the repaired bumper must be sorted from the recovered TP bumpers. Considering the difference of the chemical reaction of the paint films with dye agents, a paint film dyeing method was develop>ed. A nonrepaired bumper which is painted with acrylic- or alkyd-melamine resin becomes red and fluorescent color when a mixture of dye agent of Acid Red 52 and a solvent of lactic acid are applied. On the other hand, a repaired bumper... 

Gaviola and Wood have also shown that the fluorescence spectrum of both HgH and OH may be obtained from mixtures of mercury and water vapor irradiated with mercury resonance radiation, 2537 A. Beutler and Rabinowitch (15) considered this and the thermochemical values... 

The spectrum of Nph form on aerosil is not resolved. The wide-band fluorescence contribution relative to the molecular emission is large, afterglow is not observed. The wideband excitation spectrum at 400 nm is shifted relatively to that of a molecular form by 10 nm. For zeolites this is mainly CTC and for aerosil a bimolecular associate of Nph. When adsorbing from a vapor phase, the emission spectrum of Nph in a zeolite consists of a continuous structureless band which is a superposition of CTC and dimers adsorbed at the outer surface (Fig. 3a).In the case of co-adsorption of water vapor or hexane the spectrum transforms with the appearance of structured fluorescence and phosphorescence components (Fig.3b). The coadsorbate seems to promote breaking up of dimers and diffusion of molecules in zeolite cages. 

Another sensor type [158] utilizes the effect of water vapor on the fluorescence quantum yield of adsorbed fluorophores. Thus, a silica-gel-adsorbed perylene dy when excited with an LED at 490 nm, shows a ca 90 Fo reduction in fluorescence on going from 0 to 100% relative humidity. Although this sensor covers the whole humidity range, the response is not linear, and oxygen interferes to some atent. 

A controlled zone of heating is applied to the combustion product s flow path and to the sulfur detector reaction chamber. Water vapor produced by the high temperature oxidation of each hydrocarbon sample injection is maintained in the vaporous state throughout detection and measurement of SO2 fluorescence. Appropriate heating prevents any water vapor condensation, thereby eliminating SO2 solubility and any problems with water buildup in the analytical flow path. 

Hg from melted ice was measured by reduction to Hg(0), which was purged from solution by bubbling Ar gas. Hg(g) was trapped by metallic Au coated on sand. (Mercury is soluble in gold.) For analysis, the trap was heated to liberate Hg, which passed into a cuvet. The cuvet was irradiated with a mercury lamp, and fluorescence from Hg vapor was observed. The detection limit was 0.04 ng. Blanks prepared by performing all steps with pure water in place of melted glacier had 0.66 0.25 ng Hg/L, which was subtracted from glacier readings. All steps in trace analysis are carried out in a scrupulously clean environment. 

In this work, atomic fluorescence spectrometry (AFS) with vapor generation is used for Hg determination in different types of waters (drinking, surface, underground, industrial waste). 

Hydrophilic liquids can also cause stabilization and amplification of fluorescence Thus, Dunphy et al employed water or ethanol vapor to intensify the emissions of their chromatograms after treatment with 2, 7 dichlorofluorescein [260] Some groups of workers have pointed out that the layer matenal itself can affect the yield of fluorescent energy [261 —263] Thus, polyamide and cellulose layers were employed m addition to silica gel ones [245] The fluorescence yield was generally increased by a factor of 5 to 10 [264], but the increase can reach 100-fold [234, 265]... 

Titanium dioxide suspended in an aqueous solution and irradiated with UV light X = 365 nm) converted benzene to carbon dioxide at a significant rate (Matthews, 1986). Irradiation of benzene in an aqueous solution yields mucondialdehyde. Photolysis of benzene vapor at 1849-2000 A yields ethylene, hydrogen, methane, ethane, toluene, and a polymer resembling cuprene. Other photolysis products reported under different conditions include fulvene, acetylene, substituted trienes (Howard, 1990), phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,6-dinitro-phenol, nitrobenzene, formic acid, and peroxyacetyl nitrate (Calvert and Pitts, 1966). Under atmospheric conditions, the gas-phase reaction with OH radicals and nitrogen oxides resulted in the formation of phenol and nitrobenzene (Atkinson, 1990). Schwarz and Wasik (1976) reported a fluorescence quantum yield of 5.3 x 10" for benzene in water. 

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