Real photon method

Double Ionization-Chamber Method (Real-Photon Method)... 

In most cases, except those in earlier comparative studies between the real-photon method and the dipole-simulation method, the absolute cross-section values obtained by both methods agree with each other [27]. Comparison of obtained cross-section values between the two methods were discussed in detail [27, 2, and references therein] and summarized in conclusion [5]. It should be noted, at least briefly, that it is essentially difficult to accurately obtain the absolute values of photoabsorption cross sections (u) in the dipole-simulation experiments, and it is necessary to use indirect ways in obtaining those values as the application of the TKR sum rule, Eq. (3), to the relative values of the cross sections obtained partly with theoretical assumptions. Moreover, in some cases, in relatively earlier dipole-simulation experiments, particularly of corrosive molecules upon their electron optics with poorer energy resolutions, serious discrepancy from the real-photon experiments was clearly pointed out in the obtained absolute values of photoabsorption cross sections [5,20,25-28]. 

The real-photon method is essentially more direct and easier compared to the dipole-simulation method in obtaining absolute values of photoabsorption cross sections (o ), photoionization cross sections and photoionization quantum yields (t],). In the real-photon method, however, there is a practical need to use the big and dedicated facilities of synchrotron radiation where, in many cases, one should change the beam lines equipped with different types of monochromators depending on used photon-wavelengths—and to develop some specific new experimental techniques in the range from the vacuum ultraviolet radiation to soft X-ray. 

The absolute values of the photoabsorption, photoionization, and photodissociation cross sections are key quantities in investigating not only the interaction of photons with molecules but also the interaction of any high-energy charged particle with matter. The methods to measure these, the real-photon and virtual-photon methods, are described and compared with each other. An overview is presented of photoabsorption cross sections and photoionization quantum yields for normal alkanes, C H2 + 2 n = 1 ), as a function of the incident photon energy in the vacuum ultraviolet range and of the number of carbon atoms in the alkane molecule. Some future problems are also given. 

Brion and co-workers [14,22-25] have extensively used and applied such an experimental approach by using fast electrons as the virtual-photon source. Brion et al. [14,25] pointed out some expected characteristics of the use of synchrotron radiation in comparison with virtual photons in studies of the photoionization and photoexcitation of molecules, and clarified some necessary assumptions to virtual photons instead of real photons. It should be noted here, as described below, that these two methods, real- and virtual-... 

In this chapter, we introduce some of the most common spectroscopies and methods available for the characterization of heterogeneous catalysts [3-13], These techniques can be broadly grouped according to the nature of the probes employed for excitation, including photons, electrons, ions, and neutrons, or, alternatively, according to the type of information they provide. Here we have chosen to group the main catalyst characterization techniques by using a combination of both criteria into structural, thermal, optical, and surface-sensitive techniques. We also focus on the characterization of real catalysts, and toward the end make brief reference to studies with model systems. Only the basics of each technique and a few examples of applications to catalyst characterization are provided, but more specialized references are included for those interested in a more in-depth discussion. 

Now X-ray region has been opened to the photoacoustic spectroscopy. However, as seen in this text, the photoacoustic X-ray absorption spectroscopy is still in primitive stage. For the real applications, it seems that the sensitivity should be improved at least 10 times better than now or the photon flux should be increased by focusing or insertion devices. With the specific character of X-ray absorption, e.g. transparency of X-ray and abrupt edge shape absorption profile, this method seems to have hopeful future when the unique photoacoustic application can be conducted. 

Ferrimagnetic nanoparticles of magnetite (Fc304) in diamagnetic matrices have been studied. Nanoparticles have been obtained by alkaline precipitation of the mixture of Fe(II) and F(III) salts in a water medium [10]. Concentration of nanoparticles was 50 mg/ml (1 vol.%). The particles were stabilized by phosphate-citrate buffer (pH = 4.0) (method of electrostatic stabilization). Nanoparticle sizes have been determined by photon correlation spectrometry. Measurements were carried out at real time correlator (Photocor-SP). The viscosity of ferrofluids was 1.01 cP, and average diffusion coefficient of nanoparticles was 2.5 10 cm /s. The size distribution of nanoparticles was found to be log-normal with mean diameter of nanoparticles 17 nm and standard deviation 11 nm. 

A method for on-line monitoring of particle size distribution and volume fraction in real time using frequency domain photon migration measurements (FDPM) has been described. In FDPM the time dependence of the propagation of multiply scattered light provides measurement of particle size distribution and volume fraction. The technique has been applied to a polystyrene latex and a titanium dioxide sluny at volume concentrations in the range 0.3 to 1% [341]. 

For the situations discussed here appropriate analytical formulas for the generated states have been derived. These results have been obtained within the perturbation theory, and they agree with those of the n-photon expansion of the appropriate FD states. Moreover, we have proposed methods for checking our results numerically, and we have shown that numerical results agree very well with the analytical ones. Since we are not able to avoid dissipation processes from real physical situations, we have discussed damping processes two. It has been shown that although dissipation can play crucial role in the whole system dynamics and is able to destroy the effect of the FD state generation completely, under special assumptions these states can be achieved. 

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