Backward and forward scatter

Thus, an electron on the inverted band TTF chain corresponds to a hole with a normal band structure, and vice-versa. The interactions are shown in Fig. (1). The intrachain interactions g and gare backward and forward scattering Interactions, as in the single chain problem, and are assumed to be the same on both chains. The interchain interactions are w and These interactions... 

What for the case of small particles is called backward and forward scatter is, for the case of particles with large, flat surfaces, the sum of reflection and transmission. For infinitesimally small particles, continuum theories of diffuse reflection may be applied. As particles get larger, it becomes more likely that the terms for geometrical optics will be applied and discontinuum theories are more relevant. 

The fluorescence is generated inside the sample by photons that are already temporally dispersed. After excitation, the fluorescence is scattered backward and forward and diffuses finally to the sample surface. Kinetically, the diffusion process has to be considered as a consecutive reaction step that creates a maximum in the temporal fluorescence intensity profile. 

Figure 12, Schematic mechanism for impulsive reaction of thermal energy reaction of K with oriented CF3I. The electron is assumed to be transferred at large distance to the molecule irrespective of orientation. The molecular ion is formed in a repulsive state that promptly dissociates, ejecting the T ion in the direction of the molecular axis, and the K is dragged off by the departing T resulting in backward scattering for heads orientation and forward scattering for tails as observed.

The agreement between the theoretical and experimental data is very good. From the results, at the colhsion energy of 0.19 kcal/mol, F + H2(j — 0) product HF(v = 2) has almost no forward scattering, but primarily backward and sideways scattering, while F -I- H2(j =1) product HF(v = 2) has a very obvious forward scattering. 

Dahm and Dahm [62,63] have developed a discontinuum theoretical treatment based on the original work of Benford [67]. It is assumed that each layer of material is bounded by two parallel infinite planes. Of the radiation entering the fth layer, the total forward flux, that is, the fraction leaving the layer in the same direction, is U, and the total backward flux is n, and the fraction absorbed is at. The total forward flux includes both transmission and forward scatter and the total backward flux includes both external and internal reflection and backscatter. 

Electrokinehc measurements [20] are used to access the electrophoretic mobility /tg of the polymer particles and thereby to get information on their charges. Because of the relahvely small parhcle size of 100 to 250 nm, the measurement technique used for polymer dispersions is laser Doppler electrophoresis. Sample preparation and experimental set-up correspond to those of a dynamic light scattering experiment (Sect 3.2.2, Fig. 3-6). The only difference is a pair of electrodes immersed in the sample between which the particles are moved backwards and forwards by an al-ternahng voltage. 

Figure 2. Probability density plots of the ethyl cation product, (a) from the unlabeled reaction, (b) CH2CH3 from the labeled reaction, and (c) CD3CH2 from the labeled reaction. The backward scattered ethyl cation is more probable in (b), while the forward scattered ethyl cation is more probable in (c). Reprinted from [39] with permission from Elsevier.

Time-of-fhght spectra of the D atom products have been measured at many laboratory angles at both collision energies. Translational energy distributions can be derived by direct conversion of these TOF spectra. For the experiment carried out at 2.0 kcal/mol, Fig. 28(a) shows the total product angular distribution from 0 = —60° to 117.5°, which correspond to the forward (—60°), the sideward (30°) and the backward (117.5°) scattering directions. The direction of the D2 beam is at 0 = 0°, while the direction of the 0(XD) beam is at 0/. 90°. By definition, the forwardness and back-... 

Fig. 30. The CM product translational energy distributions at the forward (—60°), sideway (30°) and backward (117.5°) scattering direction for the 0(1D) + HD —> OD + H reaction at the collision energy of 1.7kcal/mol.

The dissymmetry method is useful especially if the instrument does not afford facilities for a wide angular scan of scattered intensities. For large particles the scattering envelope is not symmetrical and, as already indicated in Fig. 1, the forward scatter is larger than that in the backward direction. Hence the dissymmetry Z is greater than unity, where... 

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