Reaction-microscope

In this section we apply the theory developed in the preceding sections to a series of experiments carried out by Schmitt et al using the so-called reaction microscope for ultra-low energy electrons emitted from neutral target atoms. This state of the art experimental technique has enabled experimentalists to measure simultaneously the momenta of the emitted electrons and the recoiling residual-target ion and many new striking features have been found. 

J. Ullrich, R. Moshammer, A. Dorn, R. Domer, L.Ph.H. Schmidt, H. Schmidt-Bocking, Recoil-ion and electron momentum spectroscopy Reaction-microscopes, Rep. Prog. Phys. 66 (2003) 1463. 

The information provided by the highly differential cross sections that have been obtained with the help of the reaction-microscope technique [3-5] has largely terminated the debate about the physical mechanism responsible for NDSI For the situation explored in most experiments, that is, high-intensity low-frequency lasers typified by the titanium-sapphire laser (A 800 nm) at 1014 to 1015 Wcm 2, consensus has developed that NSDI is caused by the rescattering mechanism an electron that is freed by tunneling... 

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... 

In conclusion, we presented clearly the kinetics of both sorption and desorption processes. The models are based on speculation of possible mechanism(s) that governs reaction kinetics. However, these hypotheses are based primarily on macroscopic data, while sorption and desorption processes are microscopic phenomena. At best, macroscopic investigations suggest a particular mechanism may be occurring they provide little evidence that other mechanisms are not involved (Strawn Sparks, 1999). Despite such difficulties, adequate predictions of sorption mechanisms based on macroscopic observations are presented. Based on our studies, to better predict the mechanisms responsible for the kinetic processes governing adsorption-desorption reactions, microscopic as well as macroscopic data are needed. 

The polymer formed at the second stage of the reaction with magnesium chloride differs qualitatively from the polymers that are formed at the first stage and in the com"se of spontaneous reaction. Microscopic studies indicate that intensive formation of the polymer directly on the salt particles begins at the second stage. The content of nitrogen in this polymer exceeds that estimated theoretically in polyurethane. Thus a polymer is not soluble in the solvents that are... 

The task of a kinetidst is to predict the rate of any reaction under a given set of experimental conditions. At best, a mechanism is proposed that is in qualitative and quantitative agreement with the known experimental kinetic measurements. The criteria used to propose a mechanism are (1) consistency with experimental results, (2) energetic feasibility, (3) microscopic reversibility, and (4) consistency with analogous reactions. For example, an exothermic, or least endothermic, step is most likely to be an important step in the reaction. Microscopic reversibility refers to the fact that for an elementary reaction, the reverse reaction must proceed in the opposite direction by exactly the same route. Consequently, it is not possible to include in a reaction mechanism any step that could not take place if the reaction were reversed. 

Ke)ovoids Blast furnace. Highly reactive coke, Gasification reaction. Microscopic... 

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