Time-dependent emission

From these results, we have constructed a mathematical model (24) for the time-dependent emission which Incorporates three reactive Intermediates ... 

Figure 11. Time-dependent emission for aqueous acetonitrile chemiluminescence of TCPO-H2O2-imidazole system measured at 430 nm.

Correct modeling of variable diffiisivity, time-dependent emission sources, nonlinear chemical reactions, and removal processes necessitates numerical integrations of the species-mass-balance equations. Because of limitations of dispersion data, emission data, or chemical rate data, this approach to the modeling of air pollution may not necessarily ensure higher fidelity, but it does hold out the possibility of the incorporation of more of these details as they become known. 

Fig. 13. Time-dependent emission from I2(B3n0u+) — + hv following the...

The total population in either state is proportional to the total (/par + 2/per) time-dependent emission intensity from that state. The total time-dependent emission intensities in these states are given by... 

Figure 10 Reconstructed time-dependent emission spectra of WS2 nanoparticles in octane. The times (in picoseconds) corresponding to each spectrum are also given. (From Ref. 68.)...

Under our experimental conditions, multifrequency data are collected at six equally spaced emission wavelengths spanning the entire emission spectrum. For this particular case, the time-dependent emission center of gravity is then given by (27) ... 

Christiansson, J., Yu, J.W. and Neretnieks, I. (1993) Emission of VOCs from PVC flooring-models for predicting the time-dependent emission rates and resulting concentrations in indoor air. Proceedings of Indoor Air 93, Vol. 2, pp. 389-94. 

Time-dependent emission spectra from Wurtz-synthesized PMPS (Mw = 1.1 X 104), poly(methylpropylsilane) (PMPrS, Mw = 4.1 X 104) and... 

FIGURE 24. Time-dependent emission spectra of PMPS (a) 100 s irradiation and (b) 1000 s irradiation. (Reprinted from Ref. 19.)... 

Early simulation studies on solvation dynamics mostly focused on the behavior of small atomic or diatomic solutes in small molecule solvents [141,142], One of the most popular solvation probes is coumarin Cl53 (its scheme is given in Figure 11-16). Due to the fact that transition from ground to excited state in Cl53 is associated with a large molecular dipole moment increase, this has a measurable effect on polar solvents and leads to time-dependent emission spectra, shown in Figure 11-16. 

The time dependent emission frequency is finally obtained by subtracting from Sasit) the corresponding values of SK(t), defined in Eq. (7-45), calculated at the same t. 

The steady state quenching can be obtained by integrating the time dependent emission (see eqn. (16)). Using Gjj (t)e we obtain ... 

A ps absorption-emission spectrometer design which uses both pump-probe and streak camera measurement with a single-mode locked Nd-YAG laser has been described in detail.The theory of non-stationary time-dependent emission measurement and its application to ultrafast processes has been exemplified by analysis of data on the fs time-resolved emission from dye molecules in water.The power of this experimental technique is exemplified by the... 

The values of the parameters for ( )-epicatechin-(4p-- 6)-(-f )-catechin and (-)-epicatechin-(4(3—>8)-(H-)-catechin, are presented in the third and fourth lines in Table I. The lifetimes are shorter for the dimers than for the monomers. The two decay processes do not contribute equally to the time dependence of the emissions from the dimers. The preexponential factor is larger for the shorter lifetime. Two independent types of experiments that will be described, show that rotational isomerism at the interflavan bond is responsible for the heterogeneity of the time-dependence emission from the dimers. 

The excitation (absorption of a photon) and the red-shifted emission are two distinct events that are separated by a time window ranging from units to hundreds of nanoseconds depending on the fluorophore and the host system. This enables monitoring fast kinetics, because a number of molecular processes proceed on this timescale in small volumes delimited by distances comparable with the range of intermolecular interactions and affect the time-dependent emission characteristics. They include translational and rotational diffusion of the fluorophore, reorientation of molecules in the solvation shell, segmental dynamics of flexible macromolecules, and nonradiative excitation energy transfer, etc. 

The physical meaning of the individual symbols is as follows k t) is the time-dependent rate constant of the radiative depletion of the excited state, p v,t) is the normalized time-dependent emission spectmm, i.e., the denominator k f)p v, t))) describes the total fluorescence, S t), P2 is the Legendre polynomial of the second order which correlates with the mutual angular orientations of /energy states. He also employed the master equation, which describes the time change of the conditional probabilityp(/, i2 tj(j, J2o t = 0) that the fluorophore is in energy state i and... 

Detailed analyses of the time-dependent emission characteristics of single molecules (fluorescence transient) were used to show that RB molecules entrapped within the dried films are approximately four times more stable than their fresh-film counterparts (Mei, 2000). The transients also showed that the intersystem crossing rate and/or triplet lifetime are also greater in the dried films. Because of the role played by oxygen in the photochemical bleaching of RB, these results likely reflect a decrease in oxygen mobility within the dried films, and/or a reduction in the translational/rotational mobility of the entrapped dye. 

Switching from the imaging to the speetrally resolved mode of the Kerr-gated microscope reveals the time dependent emission spectrum of the nanobelts (Figure 7.5). In this case, for the sake of simplieity we placed only two nanobelts in the view of the microseope. The lumineseence intensity shown at the top... 

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