Influence of collisions

In studies of ion-molecule reactions in the gas phase, the influence of collision energy on competitive. S"n2 and. S"Ni reactions has been examined for reactions of epimeric indan-l,2-diols with the NH3-NH4+ system. Stereospeciflc. S"n2 and. S Ni pathways operate for the cis and trans derivatives, respectively. 

Boltzmann (1872, as one of the corollaries of the H-theorem)47—The Maxwell-Boltzmann distribution is the only distribution which can maintain its invariance,48 and any other distribution under the influence of collisions finally goes over into the Maxwellian one. 

Fig. 4.7. The spectrum of Sr, showing high Rydberg members and the emergence of supernumerary series members (denoted by arrows), due to the influence of collisions. Note their dependence on buffer gas pressure (after M. Nawaz et al. [148]).

When a thermal beam or a laser-produced plasma is applied, it is much more difficult to evaluate concentrations. Then the lifetimes are measured at different experimental conditions in order to observe possible influences of collisions on the measured lifetimes see Fig. 9... 

Thus far, we have represented the material system by one isolated molecule, neglecting the influence of collisions with other molecules in the gas. We must now consider the inclusion of such collision effects in the theoretical description of molecular resonances. This may be done by an extension of the foregoing treatment, regarding the ensemble of the perturber molecules as a field generating an additional effective potential IF)5 ( ) for the subspace of molecular excitations, which must be added to the complex operator W fl E) representing the rediative properties. But an essential dilference between these two quantities must be noted unlike the... 

Fig. 6. Demonstration of the influence of collision parameters and energy transfer models on the fall-off prediction for the thermal dissociation of ethoxy at 406 K. (a) MSC (CARRA MSC) versus ME (CARRA ME) approach, (b) Impact of the < down > value (calculation done with ChemRate). (c) Impact of the energy transfer model for a given value of a (see text) (calculation done with Unimol). (d) Impact of the choice of the energy transfer model if ot is adjusted to yield numerically = 200 cm (calculation done with Unimol).

Other combinations of the polarizations in the three beams would permit the Raman processes with m = m 2, m = m 1, and m = m to be investigated separately. With suitably applied magnetic fields, the influence of collisions on level crossing and anticrossing situations might be investigated. 

Eq. (13) does not yet adequately describe the coagulation process except at the very beginning. Indeed after a certain time binary particles have been formed and it will be necessary to include the influence of collisions of primary particles with these multiple ones and those of the multiple ones amongst themselves. 

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