Excitation wavelength, fluorescence

Cool and measure the intensity ol fluorescence (excitation wavelength, 365 nm emission wavelength. 455 nm). 

The fluorescence excitation wavelength used most commonly has been 278 nm with emission measured at 310 nm. 

Monitor fluorescence (excitation wavelength 365 nm, emission wavelength 450 nm) continuously for 1 h. 

I. and Follen, M. (2000) Optimal fluorescence excitation wavelengths for detection of squamous intra-epithelial neoplasia results from an animal model. Opt. Express, 7, 436-446. 

Delayed fluorescence Excitation wavelength /Ip, Fluorescence wavelength... 

FRET is defined as the energy transfer mechanism between two fluorescent molecules. When a donor molecule is excited at its specific fluorescent excitation wavelength its energy can be nonradiatively transferred to an acceptor molecule. This occurs through a series of dipole-dipole coupling reactions and is dependent on the distance between the molecules, the orientation of the molecules and the spectral properties of both. FRET techniques are widely used in fiuorescence-based detection of biomolecules, fluorescence microscopy and molecular biology applications. 

To modify the surfaces entirely (and not spatially resolved as shown with PCBAAm in the previous example) with streptavidin, the tetrazole-functionalized cellulose filter papers were immersed in a solution of maleimide-functionalized streptavidin in phosphate-buffered saline and irradiated. The success of the streptavidin immobilization was ascertained by XPS analysis. A significant increase in the C-C/C-H compared to the tetrazole-functionalized surfaces is in agreement with the presence of the protein on the cellulose fibers. Additionally, a significant increase from 6.0 at % to approximately 11.6 at% is observed in the Nls spectrum. The visual proof can be depicted by the remarkably bright fluorescence (excitation wavelength = 366 nm), whereas the control sample shows, as expected, no fluorescence. It is envisioned that the strategy can be translated to the development of novel bioactive papers and microfluidic paper-based analytical devices necessary for forthcoming developments in medicine. 

Fluorescence excitation wavelength, 220 nm interference filter (KV470) used to select emission wavelength Retention time 5.85 min Ref. 

Sun Y-P, Wang P and Hamilton N B 1993 Fluorescence spectra and quantum yields of Buckminsterfullerene (Cgg) in room-temperature solutions. No excitation wavelength dependence J. Am. Chem. Soc. 115 6378-81... 

The fluorescent emission for quinine at 450 nm can be induced using an excitation frequency of either 250 nm or 350 nm. The fluorescent quantum efficiency is known to be the same for either excitation wavelength, and the UV absorption spectrum shows that 250 is greater than 350- Nevertheless, fluorescent emission intensity is greater when using 350 nm as the excitation wavelength. Speculate on why this is the case. 

Although intended for the biochemistry lab, this experiment provides analytical students with a practical characterization analysis. Of particular interest is the use of Job s method to determine the number of TNS (2-p-toludinylnaphthalene-6-sulfonate) binding sites on calmodulin, fluorescence is measured at 475 nm using an excitation wavelength of 330 nm. 

Samples of urine are analyzed for riboflavin before and after taking a vitamin tablet containing riboflavin. Concentrations are determined using external standards or by the method of standard additions, fluorescence is monitored at 525 nm using an excitation wavelength of 280 nm. 

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. 

The same UV lamps discussed in Section 2.2.3.1 are employed to excite fluorescence. Excitation is usually performed using long-wavelength radiation (2 = 365 nm), shorter wavelengths are occasionally employed (e.g. 2 = 302 nm, DNA analysis). 

Fig. 29 Fluorescence scans of polycyclic aromatic hydrocarbons at various excitation wavelengths in combination with various secondary filters.

Fig. 17. Changes in fluorescent background on changing the excitation wavelength. Raman spectra of o-xylene using different exciting lines (a) Ar+ 488 nm (b) Kr+ 647.1 nm (c) Ar+ 514.5 nm (d) Kr+ 568.2 nm. Fluorescent background was substantially reduced in spectrum (b). (Courtesy Spex Industries, Inc.)...

Figure 4. Energy diagram for 532 nm excitation of PuF g). The 5f electron states of PuF are shown at the left. The solid arrows indicate photon absorption or emission processes. The wavy arrows indicate nonradiative processes by which excited states of PuFg may be lost. The laser-fluence dependent fluorescence decay found at this excitation wavelength can be explained in terms of a bimolecular reaction between PuFg(g) in its 4550 cm l state and PuF (g) to form PuFj(g). It is assumed that PuF (g) is formed via dissociation of the initially populated PuF state.

The ultimate in fluorescence detection is a detector that uses a monochromator to select the excitation wavelength and a second monochromator to select the wavelength of the fluorescent light. This instrument is ideal, giving the maximum versatility and allowing the... 

The derivatives have an optimum fluorescence at an excitation wavelength of 340 nm and an emission wavelength of 455 nm. The adduct is relatively stable at a pH of 9-11 but it rapidly degrades to a non-fluorescent residue at low pH values. Consequently, when used as a pre-column derivatizing reagent the pH of the mobile phase should be kept fairly high, o-phthalaldehyde has been employed for derivatization in the analysis of dopamine (29), catecholamines (30) and histamines (31). 

Figure 8. Simultaneous measurement of intracellular Ca and oxidant production in neutrophils. Cells were labeled with Quin-2 and suspended at 2 x lo cells/mL buffer. At time zero, 1 nJf FLPEP was added (upper trace in each panel). In addition, the receptor blocker tBOC was added (3 x 10" M) after 30 s to stop further binding of the stimulus (lower trace in each panel). The excitation wavelength was 3A0 nm. Top panel Quin-2 fluorescence determined on channel B (of Figure 1) using a Corion A90-nm interference filter. The crossover from the superoxide assay has been subtracted. Middle panel Oxidant production (superoxide equivalents) determined by the para-hydroxyphenylacetate assay. Fluorescence was observed at AOO nm (on channel A of Figure 1).

To confirm that the emission under each of the two maxima detected in our study was in fact that of DPA, the wavelength dependence was monitored as a function of the intensity with each one. As shown in Figure 9, the emission spectra are those of the DPA fluorescent excited state. 

Figure 3. Three-dimensional plot of the room-temperature fluorescence of a mixture of 500 ng each of benzo(a)pyrene and benzo(e)pyrene on 80% q-cyclodextrin-NaCl. Numbers along dashed lines show the approximate wavelengths (nm) represented by these lines. The excitation wavelength was varied from 250 nm (front spectrum) to 370 nm (back spectrum) at 2-nm increments. Benzo(a)pyrene emitted from approximately 380 nm to 540 nm, and benzo(e)pyrene emitted from 365 nm to 505 nm.

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