Fluorescence excitation and

Fluorescence spectra were measured at wavelength scanning of tunable dye-laser. In spite of the monochromic excitation the fluorescence spectmm has quite complex composition. Such variety of wavelengths allows to optimize fluorescence excitation and registration for any technological conditions. 

Fig. 10.1.3 Fluorescence excitation and emission spectra (solid lines) and H2O2-triggered luminescence spectrum (dashed line) of Ophiopsila photoprotein (Shimomura, 1986b, revised). The dotted line indicates the in vivo bioluminescence spectrum of Ophiopsila californica plotted from the data reported by Brehm and Morin (1977).

All samples were monitored using a Perkin-Elmer 650-10S Fluorescence Spectrophotometer. Fluorescence excitation and emission wavelengths for the PAHs in this study were obtained from Berlman (24). The resulting spectra were analyzed using an Apple 11+ computer by integrating peak areas to determine total changes in... 

Table III. Humic Fractions Fluorescence Excitation and Emission Maxima and...

Also bound to the UV-Vis spectral area is fluorescence spectrometry. It is most important with respect to those fluorescent food colorants that have been incorporated into food. In detail it helps to (1) identify a colorant by the spectral pattern of fluorescence excitation and emission spectra, (2) quantify its concentration by the fluorescence emission intensity, (3) qualify the enviromnent into which the colorant molecule is embedded, and (4) perform structural research on the food matter into which the colorant is incorporated. 

Subsequently, we reported the same experimental data as Merrill and Roberts but we have attributed the fluorescence to a (ir,ir ) transition rather than a (n,ir ) transition. We also pointed out that.the (n, ir ) state of PET is probably at higher energy than the 1 (tt.tt ) state Figure 2). We attributed the red shift in the fluorescence excitation and emission to aggregates of monomeric units fixed in specific geometry in the polymer matrix. 

Photophysical Processes in Dimethyl 4,4 -Biphenyldicarboxy-late (4,4I-BPDC). The ultraviolet absorption spectrum of dimethyl 4,4 -biphenyldicarboxyl ate was examined in both HFIP and 95% ethanol. In each case two distinct absorption maxima were recorded, an intense absorption near 200 nm and a slightly less intense absorption near 280 nm. The corrected fluorescence excitation and emission spectra of 4,4 -BPDC in HFIP at 298°K shows a single broad excitation band centered at 280 nm with a corresponding broad structureless emission band centered at 340 nm. At 77°K, the uncorrected phosphorescence spectra shows a single broad structureless excitation band centered at 298 nm, and a structured emission band having maxima at 472 and 505 nm with a lifetime, t, equal to 1.2 seconds. 

Figure 23 Fluorescence excitation and emission spectra, (a) virgin EVA sample (excitation = 280 nm emission = 360 nm) (b) EVA sample degraded for lh at 180°C (excitation = 239 nm emission = 390 nm) (c) EVA sample degraded for 1 h at 180°C (excitaton = 301 nm emission = 361 nm) (d) EVA sample degraded for 2 h at 180°C (excitation = 238 nm emission = 388 nm). Reprinted from Allen [67]. Copyright 2000, with permission from Elsevier. (This figure has been reproduced from the original in reference [67], however it would appear that the labels excitation and emission have been incorrectly inserted and should be switched for parts (b), (c) and (d).)...

The background problem can be further overcome when using a surface-confined fluorescence excitation and detection scheme at a certain angle of incident light, total internal reflection (TIR) occurs at the interface of a dense (e.g. quartz) and less dense (e.g. water) medium. An evanescent wave is generated which penetrates into the less dense medium and decays exponentially. Optical detection of the binding event is restricted to the penetration depth of the evanescent field and thus to the surface-bound molecules. Fluorescence from unbound molecules in the bulk solution is not detected. In contrast to standard fluorescence scanners, which detect the fluorescence after hybridization, evanescent wave technology allows the measurement of real-time kinetics (www.zeptosens.com, www.affinity-sensors.com). 

Griseofulvin exhibits both fluorescence and luminescence. A report by Neely et al., (7) gives corrected fluorescence excitation (max. 295 nm) and emission (max. 420 nm) spectra, values for quantum efficiency of fluorescence (0.108) calculated fluorescence lifetime (0.663 nsec) and phosphorescence decay time (0.11 sec.). The fluorescence excitation and emission spectra are given in Figure 7. 

Dramatic advances in modem fluorophore technology have been achieved with the introduction of Alexa Fluor dyes by Molecular Probes (Alexa Fluor is a registered trademark of Molecular Probes). Alexa Fluor dyes are available in a broad range of fluorescence excitation and emission wavelength maxima, ranging from the ultraviolet and deep blue to the near-infrared regions. Because of the large... 

Konev(10) and Vladimirov(n) were carrying out similar work in the Soviet Union. In 1957, Teale and Weber0 2) reported the first careful, thorough investigation of the fluorescence excitation and emission spectra of the aromatic amino acids. 

The integrated fluorescence signal //was collected with a g-in. glass light pipe and detected through a combination of dielectric and colored glass filters with a photomultiplier tube. Fluorescence excitation and elastic scattering spectra were recorded simultaneously, in order to identify the type (TM or TE) of resonance responsible for the peaks seen in the excitation spectrum. 

Compounds 1,2,3,5,10,11,12,13,14 were dissolved in EPIP (diethyl ether, petroleum ether, isopropanol 5 5 2)whereas compounds 4,6,7,8,9,15 were dissolved in THF-DE (tetrahydrofurane, diethyl ether 1 1). These solvent mixtures can be frozen as glassy samples at 77 K. The absorption spectra were recorded on a standard spectrophotometer SF-10 or Beckman-5270. The measurements of fluorescence excitation and emission spectra were made with the aid of a spectrofluorometer SLM-4800 with automatic correction of spectral response. Fluorescence lifetimes were measured with the aid of a pulse fluorometer PRA-3000. Magnetic circular dichroism (MCD) measurements were carried out in a 8 kG magnetic field using a JASCO J-20 circular dichrometer. Triplet state formation was observed for investigated compounds at the experimental set up, whose detailed description can be found in our paper (27). The optical experiments were carried out with a porphyrin concentration of 4.10- - 4.10 mol.l". In NMR investigations (Bruker WM-360) we used higher concentrations ( 5.10" raol.l ) and dried solvents (CDCl, C 2 and toluene-d0). 

Inner-filter effects. The absorption of the fluorescence excitation and emission by the specimen is referred to as the "inner-filter" effect this effect has been treated in the literature (24-27). The inner-filter effect reduces the signal levels and distorts the emission spectrum and the intensity-concentration relationship. The effect is more pronounced in right-angle fluorescence measurements (27) than in the "front face" configuration in which the fluorescence is viewed from the same side as the excitation beam. 

Electronic absorption and fluorescence excitation and emission spectra of phenazines were determined in several solvents of various polarities <1995SAA603>, and the effect of the solvent upon the spectral characteristics was studied. 

Tryptophan, tyrosine, and phenylalanine are the three natural amino acids that give rise to the intrinsic fluorescence of peptides in the ultraviolet region. Reliable, corrected fluorescence excitation and emission spectra of these aromatic amino acids were first published by Teale and Weber.M The fluorescence emission maxima of tryptophan, tyrosine, and phenylalanine in water are at 348, 303, and 282 nm, respectively. The photophysics and photochemistry of tryptophan and tyrosine have been comprehensively reviewed.1910 ... 

The laser atomic fluorescence excitation and emission spectra of sodium in an air-acetylene flame are shown below. In the excitation spectrum, the laser (bandwidth = 0.03 nm) was scanned through various wavelengths while the detector monochromator (bandwidth = 1.6 nm) was held fixed near 589 nm. In the emission spectrum, the laser was fixed at 589.0 nm, and the detector monochromator wavelength was varied. Explain why the emission spectrum gives one broad band, whereas the excitation spectrum gives two sharp lines. How can the excitation linewidths be much narrower than the detector monochromator bandwidth ... 

Fluorescence excitation and emission spectra of the two sodium D lines in an air-acetylene flame, (a) In the excitation spectrum, the laser was scanned, (to) In the emission spectrum, the monochromator was scanned. The monochromator slit width was the same for both spectra. [From s. J. Weeks, H. Haraguchl, and J. D. Wlnefordner, Improvement of Detection Limits in Laser-Excited Atomic Fluorescence Flame Spectrometry," Anal. Chem. 1976t 50,360.]... 

Visible and Ultraviolet Absorption and Fluorescence Excitation and Emission Characteristics of Florida Orange Juice and Orange Pulpwash... 

Fig. 2 shows typical fluorescence excitation and emission spectra obtained from alcoholic solutions of Florida Valencia SSOJ s. Fluorescence spectra obtained from Pineapple and Hamlin orange juices were similar to but of lower intensity than Valencia. Early in the Pineapple season the emission spectrum may appear as a flat apex (from about 310 to 333 nm). Early season Hamlin juice may produce an emission spectrum with 310 nm as the maximum dropping to an inflection at 333 nm. As the fruit matured 333 nm became the emission maximum. Maximum excitation and emission (for the three varieties) were also evident at 290-93 and 343 nm, respectively, producing excitation spectra similar to Fig. 2 (shoulder at 283 nm and slight inflection changes at 270 and 302 nm). Valencia variety exhibited greater fluorescence than Hamlin or Pineapple varieties. 

Figure 4. Comparison of fluorescence excitation and emission spectra of orange juice (----) and orange pulpwash ( — )...

Visible and ultraviolet absorption and room temperature fluorescence excitation and emission spectra obtained from alcoholic... 

The fluorescence excitation and emission spectra of the electrogenerated fused benzothiophene oligomers [poly(39) and poly(41)] show the existence of dramatic red shifts of the fluorescence maxima and important increases of the fluorescence intensity relative to the parent monomers. These results suggest the existence of extended electronic conjugation in the oligomer chains. Poly(39) and poly(41) showed a well-structured excitation band with maxima at about 335 nm and 395 nm, respectively. These excitation maxima are strongly red shifted by about 50 and 108 nm, respectively, against the 39 and 41 excitation spectra. The emission spectra are characterized by a relatively wide, poorly structured band, centered at 410 nm and 445 nm, respectively. These emission maxima also present dramatic red shifts relative to the emission spectra of the parent monomers. 

The electropolymerization of 3-methoxythiophene (MOT) was performed in an aqueous micellar medium containing sodium dodecylsulfate (SDS) as a surfactant. The electronic absorption spectra, the fluorescence excitation and emission spectra, and the quantum yields of 546, were measured in different solvents of various polarities and hydrogen bond abilities (89SM(28)C487 98SM(93)175 00JF107 00POLLDG4047 ... 

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