Coherent scattering region

When the crystalline domains (or crystallites, i.e. coherently scattering regions) have a finite extension, the diffracted intensity is no longer confined to a point, but spreads over a region whose size and shape are related to the crystallite size and shape. 

Particle sizes (coherent scattering region) of Ti02 samples were calcu-... 

Diffraction patterns of the nanosized anatase and r -Ti02 showed that sample S30 referring to anatase contains trace amounts of [3-Ti02(JCPDS 46-1238). Analysis of the obtained size values of coherent scattering regions (L-values) of the il-Ti02 and anatase samples showed thatZ = 50 (2) A and L =100 (5) A, that is, crystallite sizes for the il-Ti02 samples are substantially less. 

Sample composition Ssp, Average pore diameter, nm Phase composition, % mol. Coherent scattering region, mn... 

Ag dispersion was determined by various methods size of coherent scattering region (average size dv) was obtained by X-ray method surface average size ds - by adsorption method size distribution of Af particles was obtained by the method of small angle X-ray scattering (SAXS) and TEM. The two last methods were applied to determine the most probable size of Ag particles dp. 

Conditions (2) and (3) are equivalent to the Fraunhofer or far-field approximations in ordinary optics. The coherently illuminated region with usual laboratory X-ray sotuces is a few micrometres across. We therefore expect this theory to be useful in the cases of weak scattering but to be seriously awry for strong scattering. 

A variably delayed probe pulse can be used to monitor the time-dependent vibrational oscillations and decay through coherent scattering ( diffraction ), yielding data like that shown in the simulation in Fig. 3a. In this simulation, the excitation and probe regions are overlapped spatially, and the decay of signal is due to damping and dephasing of the phonon-polariton response. From data of this form, the polariton frequency co and... 

Coherent scattering lattice regions (crystallites) Agglomerates... 

The traveling-wave excitation described by Eq. (21) affects the dielectric tensor, as described by Eq. (15). The effects can be detected by a variably delayed probe pulse that is phase matched for coherent scattering, that is, collinear (in practice, nearly collinear) with the excitation pulse and the vibrational wave vector. Since the probe pulse follows the excitation pulse through the sample at the same speed c/n (neglecting dispersion), it surfs along a crest or null of the vibrational wave. The probe pulse therefore encounters each region of the sample with identical coherent vibrational distortion. 

A transition region with no coherent scattering signal (dotted part in Fignre... 

Estimation of the relative intensity of the autoionization process [27] has shown that the second-order process intensity constitutes 10-15% of the first-order process intensity. Based on the results obtained and the dipole approximation for electron transitions [28], the authors of [27] draw the conclusion that the SEFS structure is formed in the process of coherent scattering of a secondary electron emitted from the valence band as a result of excitation by an incident electron (the first-order process). By contrast, the intensity of autoionization, i.e., the second-order process, was estimated [29-31] with hydrogenlike wave functions. The autoionization intensity in the region of the existence of the SEFS spectrum was shown to be comparable to the intensity of the first-order processes. 

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