Cross section of reaction

There is a little information available from repeller studies. In their paper on methanol, Thynne et al. (40) present, without analysis, data on the variation of the phenomenological cross-sections of Reactions J and K with the ion-exit energy obtained from conventional low pressure measurements. These data can be used to examine the dependence of k(Ee) upon Ee via the relation ... 

Figure 3.16 Schematic of Si-chip catalyst membrane micro reactor. Top view (A), end-on cross section of reaction channel (B) side-view cross section of reaction channel (C) [60].

Reactions (19.35), (19.36) have been studied theoretically for NA = X Xt on several occasions, and n-resolved cross-sections, obtained within the Grizinsky-Bauer-Bratky (GBB) model [59,60], are presented in [21]. (Total experimental cross-sections for these reactions for the X1T +(n = 0) initial state are given in [14].) The simplicity of GBB model permits to perform v—v resolved cross-section calculations also for transitions from excited (N > 2) states, but such calculations have not been published. It should be mentioned, however, that the accuracy of GBB method is (at best) within a factor of two, and more accurate quantal calculations of the cross-sections of processes (19.35), (19.36) are desirable. For transitions from the initial NA states with N > 3, the cross-sections of reactions (19.35), (19.36) within a given 1,3ylSj -series of states can be scaled (approximately as N2). 

Reaction (9) was directly observed by Pettersson and Lindholm (1963) in their tandem mass spectrometer, and its rate was measured by Derwish et al. (1964b), who demonstrated that the cross sections of reactions (8) and (9) are comparable, the respective values being 2-7 and 2-9 X 10 cm molecule", at a repeller field of 10 V cm . Reaction (10) was described by Pettersson and Lindholm (1963) and repeatedly observed in the study of ion-molecule reactions in propane. 

Given the relatively low cross sections of reactions (19), exothermic reactions with trace species such as ozone ... 

Figure 8. Schematic cross-section of reaction zones in subseafloor hydrothermal systems (from Woodruff and Shanks 1988). Used by permission of the American Geophysical Union.

Later, a very fine investigation was carried out on this reaction by Chupka et al. [204]. Producing their reactant H2 ions in selected vibrational states, or even in selected rotational states, by the use of their high-resolution photoionization mass spectrometer, they studied the cross-section of reaction (123) as a function of vibrational and kinetic energy of the reactant ions. The found that the cross-section decreases as vibrational excitation increases when ion kinetic energies are low, but the reverse is true when ion kinetic energies are high. 

The cross-section of reaction (125), on the other hand, was found to be nearly independent of vibrational energy. Although a direct mechanism... 

Rutherford and Vroom [224] and Kaneko and Kobayashi [225, 226] have investigated the effect of excited ions in the primary ion beam on the measured cross-section of reaction (127). The role played by these excited ions in producing the peculiar data of this reaction (see Section 5.4) has been open to question. 

Combining the cross-sectional data obtained from 50 eV electron impact on Oj with the result of the abundance measurements by Turner et al. [221] (see above), the cross-sections for reaction (116) for excited ions (O ) alone can be estimated. The results obtained are 26, 18, 13, 11, and 6 (all in units of 10" cm ) at 0.65, 1, 2, 3, and 10 eV, respectively. The corresponding values for the ground state ions alone as obtained from 21 eV electron impact on CO2 are approximately 0.35, 0.4, 0.5, 0.8, and 0.8, respectively, in the same units. It is seen that the excited states of play an important role in the cross-section of reaction (116). 

Some information on the effect of translational energy on the reactions of photochemically generated atoms other than hydrogen has appeared. The cross-section of reaction (87) decreases with increasing energy, so that chlorine atoms of initial energy 58 kJ mol produced by photolysis of CU at 337 nm react with HI faster after thermalization. ... 

Matter distribution can be determined from elastic p, n, a scattering, it" ", K meson scattering, and cross sections of reactions induced by p, n, antiproton, it, and K beams. 

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