7-reaction transverse cross-section

The reaction-microscope technique is capable of measuring a fully (sixfold) differential cross section, by detecting the three-dimensional momenta of two particles of opposite charge, viz. the ion and one electron. Such a fully differential measurement was recently accomplished [7]. However, the very first experiments were content with recording the NSDI yield as a function of two momentum components of the ion, one parallel (P ) and one transverse (P ) to the linearly polarized laser field, while the second transverse component (P ,2) was integrated over. In terms of the amplitude (4.1), this corresponds to the momentum distribution... 

We consider the following physical situation. A first-order exothermic reaction runs on a smooth, nonporous catalytic element having a length L (thread, fiber, tube). Assume that there is no temperature distribution at the element cross-section, thus reducing the analysis to a one-dimensional case. Assume also that the reaction runs under conditions of transversal flow, and the heat and mass transfer between the catalyst surface and the bulk-flow are described by the effective coefficients a and respectively. Under these assumptions, the model can be written in the form of two equations, one describing the heat balance in the solid catalyst phase, and another the reactant balance in the gaseous phase of a certain characteristic layer adjacent to the catalyst surface ... 

Compared with normal wood, this tissue is characterized by shorter tracheids, higher lignin and hemicellulose content, and lower cellulose content. This reaction wood is easily identified on smooth surfaces, in particular in a transverse view. When compression wood is formed, the growth rings appear darker, reddish brown, and often wider than on the opposite side. Therefore, when compression wood develops in the same side for several years, the cross section of the stem tends to be oval with an eccentric pith in the core this is typical of branches or stem of bent trees. 

The major application of this technique, principally by Lindholm and co-workers (see Chapter 10), has capitalized on the above limitation in a study of charge-transfer processes, where the products may exhibit a thermal energy distribution. Even in this application, cross sections are difficult to obtain because the sampling volume is not well defined. Lindholm has been careful to quote only Q values which are estimates of the relative reaction efficiencies. There is another reason why any such cross section so measured may be unreliable. It is plausible, and indeed it has recently been demonstrated, that charge-transfer reactions may yield some products which are forward-scattered in the laboratory framework these would result from collisions with small impact parameters. To the extent that these products will not be detected in a transverse tandem machine, the measured cross section will be underestimated. 

In the jet method, for mixed reactants the concentration of active species R- due to reaction 6 decreases along the jet. This decrease, which is experimentally detected by spectrometiic methods, allows to be detmmined. Difficulties iqjpeared in this method are associated widi the decay of active species in collisions with the reactor surface, necessity to take into account longitudinal and transversal difiusion, and nonuniformity of die distribution of the flow velocity over the tube cross section. Expoimoits are usually performed under conditions where the distribution of the concentration of active species and the nonuniformity related to Poiseuille s flow can be neglected. 

C) During deton, the hot products of reaction pierce the unexploded portions of expl and this is supposed to be possible because the pressure in the cross (transverse) sections of the deton wave is not evenly distributed... 

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