Scattering cross section ratio

Rl optical anisotropy (from scattering cross section ratio, RLS)... 

The ratio of elastically to inelastically scattered electrons and, thus, their importance for imaging or analytical work, can be calculated from basic physical principles consider the differential elastic scattering cross section... 

Figure 11.15 shows Asano s calculations of extinction by nonabsorbing spheroids for an incident beam parallel to the symmetry axis, which is the major axis for prolate and the minor axis for oblate spheroids. Because of axial symmetry extinction in this instance is independent of polarization. Calculations of the scattering efficiency Qsca, defined as the scattering cross section divided by the particle s cross-sectional area projected onto a plane normal to the incident beam, are shown for various degrees of elongation specified by the ratio of the major to minor axes (a/b) the size parameter x = 2ira/ is determined by the semimajor axis a. 

RBS is capable of distinguishing the isotopes of heavier elements, however the more common use of RBS is for the determination of stoichiometric ratios and composition as a function of depth. RBS was used in another study of plasma grown oxide films on GaAs to determine the ratio of 0 to Ga and As (31). Based on the well known ion scattering cross-sections, a ratio approaching 1.5 was found for films greater than lOOoX thick. The composition of the oxide inferred from this result is a mixture of Ga 0. and As203<... 

Results are reported as contour plots of the cross-section ratios vs. the phase < and the parameter s =, x2/(l + x2 ). The value s = 0 corresponds to scattering the state with mx = 1 and s = 1 corresponds to scattering from the state m2 = 0. The ratio of cross sections is seen to vary from 0.05 to 0.079, sfi maximum and minimum that are well outside (up to factors of 1.22 and respectively) of the range of results for scattering from a single m state. Thus, i ratio of cross sections can be increased or decreased by approximately 20% f coherent control effects. 

The albedo of a dust grain is defined as the ratio of its scattering cross section to its cross section for total extinction. From the observations, values of the albedo as high as 0.9 at X 1500 A are obtained. A particle with no... 

The differential Raman scattering cross sections and depolarization ratios in the Fermi resonance region of carbon disulphide CS2 were measured and interpreted in terms of three bond polarizability parameters and the cubic force constant k 22 (Montero et al., 1984). 

Another intriguing quality of Raman spectroscopy is its capability to measure local temperature quantitatively and precisely. This is possible in two distinct ways, arising due to two different characteristics of the Raman spectra in crystalline solids. The first characteristic is the presence of the phonon occupation number in the Raman scattering cross section in accordance with (17.3). While the relation to temperature of the strict intensity of a particular phonon peak is obfuscated by the numerous other components of the Raman scattering cross section, taking the ratio of integrated intensities of the Stokes (1 ) and anti-Stokes (Ias) peaks provides the following relationship by which to measure temperature ... 

A knowledge of the frequency-dependent polarizability functions and their gradients allows the Raman scattering cross sections and depolarization ratios... 

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