Intensities, relative emission

Relative emission Intensity measurements were made at 475 nm for tin analysis, the emission maximum for the tln-flavonol complexes examined In this work. Emission spectra are uncorrected. 

Fig. 5 Absorption and fluorescence emission spectra of the 3-hydroxychromone dye F4N1 in the absence (black) and presence (red) of a local electric field, which promotes the excitation charge transfer leading from the ground state to the N state. In the presence of the local electric field, the energy of the N state is reduced, causing a red shift of the N emission peak and an increase in its intensity relative to the T emission peak. The change in relative intensities of the N and T peaks reflects a shift in the excited state tautomeric equilibrium toward the N state...

Fig. 11. Relative emission intensities of RufTAPlj as a function of the ratio DNA phos-phate/complex P/C) in air saturated phosphate buffer (3 mM) = 600 nm 2, . = 450 nm) [adapted from Kelly JM, Me Connell D, OhUigin C, Tossi AB, Kirsch-De Mesmaeker A, Mas-schelein A, Nasielski J (1987) J. Chem. Soc., Chem. Commun. 1821]...

A test of this dependence is shown in Figure 5 for the fluorescence quenching observed in a number of ZnTPP-acceptor solutions at 77 K. The time-dependence of the relative emission intensity, l(t)/Io> may be given by... 

Lee and coworkers postulated the involvement of 50 and 51 (Ar = 2,4-dinitrophenyl) as two HEIs formed in parallel in the uncatalyzed reaction of DNPO and hydrogen peroxide in the presence of perylene. Due to the experimental observations of light emission from the reaction of DNPO and TCPO also in the absence of hydrogen peroxide, Lee and coworkers postulated the involvement of a nonperoxidic HEI (additionally to 51 and 3, 48 or 52) under these conditions. However, neither chemiluminescence quantum yields nor even relative emission intensities have been reported. Furthermore, it was shown " that the intensities and the chemiluminescence quantum yields in the absence of hydrogen peroxide are five orders of magnitude lower than in the presence of 10 M H2O2, indicating that the proposed additional pathway is of extremely low efficiency for excited-state... 

Controlled double-potential techniques have also allowed measurement of relative emission intensity as a function of the time in which each of the potential steps is allowed to proceed. Comparisons of the emission intensities obtained with those predicted by mathematical models68,69 have been used as mechanistic evidence,85,67 see Sect. IV-B. 

The fluorescer structure studies indicate that relative emission intensities in a series of similar compounds is a function of the fluorescence efficiency and its spectral distribution, the stability of the ion radicals and the solubility of the fluorescer.17 Emission intensity seems to reach a maximum near 10 2M in dimethylformamide6 and for many fluorescers of interest this concentration cannot be achieved (cf. Fig. 5) for lack of solubility. 

Utilizing the methods of heterochromic photometry, the relative emission intensities of all the bands was obtained. It was found that these did not change over the concentration range from 0.2 to 0.02 per cent. 

From the data of Hoogschagen and Gorter (104), the oscillator strength of the 5D4-+7F6 transition was obtained. By means of the Ladenburg formula, the spontaneous coefficient A46 was calculated. Using the relative-emission intensities, the rest of the A4J spontaneous-emission coefficients could be calculated. From these and a measured lifetime of 5.5 x 10 4 sec at 15°C, he calculated a quantum efficiency of 0.8 per cent. Kondrat eva concluded that the probability of radiationless transition for the trivalent terbium ion in aqueous solution is approximately two orders of magnitude greater than for the radiation transition. 

E-Type Delayed Fluorescence. (Produced by thermal activation of molecules from the triplet level to the upper singlet level.) The contour of its spectrum is identical with that of normal (short-lived) fluorescence. The intensity relative to that of the triplet-singlet emission decreases exponentially with the reciprocal of the absolute temperature and the activation energy is equal to the frequency difference between the two bands. The intensity is proportional to the first power of the rate of absorption of exciting light. The lifetime is the same as that of the triplet-singlet emission in the same solution under the same conditions. 

The Stern-Volmer equation says that, if we measure relative emission (0/q) as a function of quencher concentration and plot this quantity versus [Q], we should observe a straight line. The quantity <3>0/Oq in Equation 19-25 is equivalent to /,/Iq, where /0 is the emission intensity in the absence of quencher and Iq is the intensity in the presence of quencher. 

Figure 7.20 Selection of emission spectra of laser dyes. Horizontal axis, wavelength in nm vertical axis, relative emission intensity on a logarithmic scale...

Fig. 19.5 Typical plots (relative emission intensity lo/I and relative emission lifetime to/t) for the quenching of photoexcited state against quencher concentration, (a) Dynamic mechanism, (b) Static mechanism, and (c) Combined mechanism.

Figure 1. Relative emission intensity monitored at 600 nm vs. temperature in 1M OH /lM S2 electrolyte of CdS Te (100 ppm) excited at open circuit with 514.5 and 501.7 nm (O) light in identical geometries. The excitation intensity at 501.7 nm is 17X that at 514.5 nm in order to match approximately room temperature emission intensities.

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 reasons behind a complex behavior in the relative emission intensity or lifetime vs quencher concentration plots (typically the quencher is the analyte species or a third party, the concentration of which depends on the analyte level [44]) are manifold and may be dependent on the nature of the inorganic support surface, its interaction with the organic polymer matrix, the... 

A very interesting approach for specific immunoassays was recently reported by Wang, Yang, and Tan [108]. They employed silica nanoparticles of varying sizes with different mixtures of [Os(bpy)3]2+ and [Ru(bpy)3]2+ incorporated in the particles, imparting different relative emission intensities for the Ru and Os chromophores. The nanoparticles were then modified with either mouse or human IgG antibodies and exposed to microspheres modified with, for instance, anti-mouse IgG. Luminescence results revealed that the mouse IgG nanoparticles associated specifically with the anti-mouse IgG microspheres. Further, mixtures of the microspheres modified with anti-mouse and anti-human IgG could be distinguished because of selective doping ratios of the nanoparticles with the Os and Ru complexes. 

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