Wavelength-dependent constants

R26 are shown. From Fig. 4, we can see that the dynamics of the initial ET depends on the probing wavelengths. This phenomenon is usually called the wavelength-dependent kinetics. Obviously, the one-step model cannot account for this wavelength-dependent kinetics phenomenon because in this case only one rate constant is involved. In order to understand the origin of wavelength-dependent kinetics, the detailed mechanism of the initial ET in RCs should be constructed. 

If the probe display shifts in absorption and/or emission spectra, the apparent dissociation constant will depend not only on the measured parameter but also on the excitation and emission wavelengths. For probes that display a shift in the absorption spectrum on analyte binding, the value of f/ bdepends on excitation wavelength, which affects the value of Koa (see Eq. (10.24)). For probes which display shift in emission spectrum the value of may depend on observation wavelength. The... 

Again the radiative association kinetics described above allow a direct comparison for some realistic values of k and k. For most chemically activated systems at the threshold for unimolecular dissociation, the observed radiative rate constants are of the order of 10-100 s and hence are much below the values expected for k of about 10 s . Therefore, the first limit is most likely to be valid, with the interesting conclusion that the observed unimolecular dissociation rate constant will depend only on the photon density and the absorption cross section (rate constant) at a given wavelength. 

Does this mean that the resolution of an acoustic microscope is undefined No, because the Sparrow criterion gives a perfectly good experimental measure indeed, detailed studies have been made of the transfer function and the spatial frequencies present in a line scan (Block et al. 1989 Heygster et al. 1990). What is clear is that, whatever the exact numerical constant in (3.3), the resolution is proportional to the wavelength in the fluid Ao. The way to improve the resolution is therefore to make the wavelength smaller. The wavelength depends on the velocity of sound in the fluid v0 and the frequency / such that... 

The magnitude of the proportionality constant a depends on the strength of the coupling between nucleus and electrons. It can be determined by extrapolating the measured refractive index to infinite wavelength, as a result of the relations that exist between oo, 6 (dielectric constant) and a, which are... 

Some evidence for ground state CT complex formation is also obtained from such quenching experiments when excited at the second absorption band which has a maximum at 260 nm. A wavelength dependence of quenching constant is observed (Fig. 11.5). 

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