Fluorescence intensity ratio

Figure C2.3.18. Vibronic peak fluorescence intensity ratio (III/I) as a function of SDS concentration for 0.1 % PEO solutions o, —35 000 Daltons —600 000 Daltons). Open symbols are for aqueous solution without added salt, and filled symbols are for 100 mM aqueous NaCl. Reproduced with pennission from figure 2 of [111].

Fig. 4 The histograms of the fluorescence intensity (ratio red/green) for the secretory cells (the amount of cells fluorescing in green 520-540 nm) of developing leaf from Achillea millefolium. Upper histograms - leaf without developing secretory cells lower histograms - after the appearence of secretory cells. (The amount of red fluorescing cells on the leaf surface decreased as can be seen from smaller heights of histograms).

Figure 14 Fluorescence intensity ratio of acceptors at 417 nm and donors at 360 nm plotted against the molar fraction of MP-CUA in mixed LB films with (O) PA and ( ) AA The dotted line shows the calculated dependence by Forster energy transfer. 

When a fluoroionophore contains two fluorophores whose mutual distance is affected by cation complexation, recognition of this cation can be monitored by the monomer/excimer fluorescence-intensity ratio (see Chapter 4, Section 4.4.1 for ex-rimer formation). Cation binding may favor or hinder exrimer formation. In any case, such a ratiometric method allowing self-calibration measurement is of great interest for practical applications. 

Pyrene carboxaldehyde and a series of pyrene carboxylic acids were found useful as fluorescence probes in describing the constitution of inverted micelles of certain calcium alkarylsulfonates in hydrocarbon media. 1-Pyrene carboxaldehyde is a convenient probe for studying the particle sizes of micelles in the region of lOOA. A series of graded probes, pyrene carboxylic acids with varying alkyl chain length, have been used to determine internal fluidity and micro-polarity as a function of distance from the polar core of these Inverted micelles. Pyrene exclmer to monomer fluorescence intensity ratio and fluorescene lifetime provided the means of measurement of internal fluidity and micropolarity, respectively. 

It can be seen that the excimer to monomer fluorescence intensity ratios for the same molar ratio of probe to sulfonate are much smaller in the sulfonate A system than in the sulfonate B system. For both sulfonates A and B, the intensity ratio tends to Increase with the chain length of the carboxylic acid. The variation is distinctly established for sulfonate B micelles, but less so for sulfonate A micelles. The results indicate that the internal fluidity of the micelles decreases from the edge of the polar core to the continuous hydrocarbon medium the gradient is steeper for sulfonate B. 

Figure 15b illustrates the dependence of fluorescence intensity ratios on the f0 function prescribed by (21), with different assumed values for the interaction number. 

Figure 15 c gives the graphical representation of the fluorescence intensity ratios as prescribed by (23). 

Fig. 11 Temperature dependence of fluorescence intensity ratio (h/h) of pyrene as an imitated drug/catalyst in deionized water in the presence of PNIPAM-g-PEO chains, where the concentration of pyrene is 2 x 10-7 M [67]...

Figure 16 Plots of fluorescence intensity ratio /340//335 from excitation spectra of pyrene in aqueous solutions in presence of —o— PS-denrfr-(NH2)8 and —O— PS- fe rfr-(NH2)l6...

Trpkovski, S., Wade, S. A., Baxter, G. W. and Collins, S. F. (2003). Dual temperature and strain sensor using a combined fiber Bragg grating and fluorescence intensity ratio technique in Er[sup 3+]-doped fiber. Review cf... 

In the present study, a FLIM measurement system was constructed and applied to Halobacterium salinarum (Hb. salinarum) loaded with 2, 7 -bis-(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) to obtain information on the intracellular environment as well as the intracellular pH in each ofthe cells [9-12]. Hb. salinarum belongs to the family of extreme halophilic archaebacteria, and considerable attention has been paid to this bacterium in relation to proton transport, phototaxis or the adaptation of an organism to extreme environments [13-15]. Intracellular pH is an essential parameter for Hb. salinarum in the regulation of intracellular processes [14, 16, 17], and fluorescence intensity ratio methods have been used to measure the intracellular pH [18,19]. The... 

The description given here is confined to the method developed by Abuin and Lissi demonstrating the use of fluorescence as a method for determining partition coefficients for solutes that are not by themselves fluorescent. The method is based on the observation that an additive changes the characteristics of the fluorescence of a micelle-incorporated probe such as pyrene. It is assumed that the fluorescence intensity of micelle-incorporated pyrene is determined only by the mole fraction of solute in the micellar pseudophase. The probe fluorescence intensity ratio f/I in the absence and presence of a solute is measured as a function of the solute concentration at different surfactant concentrations. From plots of the intensity ratio vs. the solute concentration at different surfactant concentrations we obtain a set of additive concentrations c,o, that corresponds to the same f/I value and thereby the same and K. Ctot is related to the concentration of micellized surfactant, through the following equation ... 

A similar experiment was performed for the PMMA film doped with 1-ethyIpyrene. As shown in Fig. 7, fluorescence spectra were composed of a structured monomer and red-shifted broad excimer bands. As molecular diffusion during fluorescence lifetime is negligible in film, the latter band is due to the ground state dimer of pyrene which is easily formed under its high concentration. It should be notified that the fluorescence intensity ratio of the monomer to excimer emissions under the TIR condition is larger than that under the normal one. This may indicate that the pyrenyl concentration in the interface layer is also lower than that in the bulk. 

Excimer-to-Monomer Fluorescence Intensity Ratio (I /I). In most probe studies using excimer formation, as mentioned above, the excimer-to-monomer fluorescence intensity ratio I /I is used as an experimental criterion (11,17-19). 

From the temperature dependence of the excimer-to-monomer fluorescence intensity ratio I /I, for Py and IPy(3)IPy on reversed-phase Si-C. g, the activation energy E of surface diffusion was determined, using [2]. Values for E of 19 and 40 kJ/mol were found... 

Figure C2.3.18. Vibronic peak fluorescence intensity ratio (IIl/l) as a function of SDS concentration for 0.1 %...

In this letter, it has been report the modification of a localized area of an oxyfluoride glass doped with Nd ions under continuous Ar laser irradiation. The local transformation into a glass ceramic structure has been made controlling the temperature of the devitrification process through the monotorization of the fluorescence intensity ratio and the time resolved fluorescence. 

Figure 5. The relative fluorescence intensity ratio Irb/Ir6g as a function of pH in aqueous solutions of PA-I8K2. The concentrations of PA-I8K2 are 0.01 (O) and 1 giL (A).

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