Fluorescence solution

The phase shift is measured by comparing the phase of the fluorescence with the phase of light scattered by a cloudy but non-fluorescent solution. 

Fluorescein reaction. Fuse together in a dry test-tube o-i g. of succinimide, O l g. of resorcinol and 2 drops of cone. HjSOi, Cool, add water and then NaOH solution in excess. A green fluorescent solution is obtained. 

Purified by recrystn from xylene. Gives yellow-green fluorescent solutions at pH 8.2-9.5, [IR Schnopper et al. Anal Chem 31 1542 7959.] With AcCl naphthol AS-D acetate is obtained m 168-169°, and with... 

The amorphous alkaloids include a substance, giving fluorescent solutions in organic solvents, which is thought to be a decomposition product of ibogaine. 

AM Weiss, AJ Grodzinsky, ML Yarmush. Chemically and electrically controlled membranes Size specific transport of fluorescent solutes through PMAA membranes. AlChE Symp Ser 82 85-98, 1986. 

The spectroscopic properties of the solute-solvent system accounting fluctuations of solution structures can be analyzed using a simple model that includes a fluorescent solute and its immediate surrounding contributing to full potential of... 

Although numerous materials and fluorescing solutions were described in the seventeenth and eighteenth centuries, and in spite of the fact that since around 1860 mineralogists started the use of fluorescence for detection of mineral deposits, little progress was observed concerning the explanation of the phenomenon, and it was only around the mid-nineteenth century that important achievements were made in the study and understanding of luminescence phenomena. 

It is worth pointing out that many artifacts can alter the measurements of emission anisotropy. It is necessary to control the instrument with a scattering non-fluorescent solution (r close to 1) and with a solution of a fluorophore with a long lifetime in a solvent of low viscosity (r x 0). It is also recommended that the probe concentration is kept low enough to avoid interaction between probes. 

Carbon disulfide quenches the fluorescence of anthracene quite efficiently,145,149 but seems to have little effect on its triplet lifetime.147 Diphenylanthracene in benzene fluoresces with a quantum yield of 0.8 and shows a high sensitivity to the oxygen concentration in photooxygenation reactions. With about 1 vol% of CS2 present, AC>2 is practically independent of [02] (> 10"5 mole/liter). In jjoth cases, where carbon disulfide was either used as solvent or was added to an otherwise strongly fluorescent solution, the quantum yields of photooxygenation followed... 

In photoassociating solvents (e.g., benzene and its alkyl derivatives) the transfer of electronic excitation energy from solvent to fluorescent solute is characterized37,63 by rate constants kt which are approximately twice those computed from the less approximate form of Eq. (7) ... 

Naphthol AS-D (3-hydroxy-2-naphthoic-o-toluide) [135-61-5] M 277.3, m 1196-198 . Purified by recrystn from xylene. Gives yellow-green fluorescent solutions at pH 8.2-9.5, [IR Schnopper et al. AC 31 1542 1959]. With AcCl naphthol AS-D acetate is obtained m 168-169 , and with chloroacetyl chloride naphthol AS-D-chloroacetate is obtained [Moloney et al. J His toe hem Cytochem 8 200 1960 Burstone Arch Pathology 63 164 1957],... 

Equation (2) also shows how the intensity of fluorescence varies when the frequency of the exciting light varies. For a given solution the fluorescence intensity is proportional to 7oe0 and for many substances in solution the fluorescence efficiency () is approximately independent of the excitation frequency. Thus, if the intensity of exciting light is kept constant as the frequency is varied, the fluorescence intensity will be proportional to e, the molecular extinction coefficient of the solute. Hence the true excitation spectrum frequently corresponds closely to the absorption spectrum of the compound (see Fig. 2). Spectrofluorimetry can thus be used to measure the absorption spectra of fluorescent solutes, but at concentrations far lower than could be measured directly with an absorption spectrophotometer. It has the further advantage that the... 

The red color of adrenochrome methyl ether (8) solutions is rapidly discharged on addition of alkali, with the formation of a dirty brown, essentially non-fluorescent, solution from which an unidentified dark grey amorphous product was obtained on acidification,110 possibly 5,6-dihydroxy-3-methoxy- -methylindole (35) and not 5,6-dihy-... 

F. Sodium Bisulfite Addition Product Formation The red color of aminochrome solutions is rapidly discharged by the addition of sodium bisulfite with the formation of pale-yellow fluorescent solutions. The reactions of adrenochrome with sulfites and bisulfites have been the subject of several previous reports.12, 102.109.118,119.123,128,148.182.155. 158,173-177 Although it was originally... 

Two important quantities relating to fluorescent solutions are the mean life of the excited state and the quantum yield. In the ideal case where every excited molecule loses its energy by radiation the emission intensity decays exponentially with time, and the time to drop to 1/e of the original intensity is called the radiational mean life. If only a fraction F of the molecules radiate, the remainder being degraded in some other competitive way, then the actual life, as would be found by measurement, is smaller by the fraction F. This relationship, however, would not be true if some of the molecules were almost instantly degraded by solvent molecules after excitation. Direct determinations of mean lives require special apparatus, sometimes of doubtful accuracy, because of the short times, 10-7 to 10 9 sec., involved. Although much work has been done in this field with scintillator crystals and solutions, there are... 

Kim and Johnston (27), and Yonker and Smith (22) have used solute solvatochroism to determine the composition of the local solvent environment in binary supercritical fluids. In our laboratory we investigate solute-cosolvent interactions by using a fluorescent solute molecule (a probe) whose emission characteristics are sensitive to its local solvent environment. In this way, it is possible to monitor changes in the local solvent composition using the probe fluorescence. Moreover, by using picosecond time-resolved techniques, one can determine the kinetics of fluid compositional fluctuation in the cybotactic region. 

Experimental proof for the above-described hypothesis was found by taking microscopic photographs of the textile structures in dry and wet conditions using a fluorescent solution. From these images, it could be seen that air bubbles were indeed trapped in the wet structures, but due to the more regular structure of the non-woven fabrics compared with woven and knitted fabrics, much less air was trapped. Confirmation for the dissolution of these bubbles is found by the absence of air when the textile electrodes were immersed for about 3 days in the fluorescent solution. 

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