Collision, inelastic

The recoverability or restitution of the kinetic energy during a normal collision between two objects can be represented by the coefficient of restitution defined by Eq. (2.3). Note that the coefficient of restitution cannot be used as a criterion to judge whether a collision is elastic or not unless the collision is solely considered as a normal collision. For example, the sliding at contact for the collision between two elastic spheres will make the collision inelastic while the value of the coefficient of restitution in this case is equal to 1. 

Attempts to generalize the developed model to dispersions for which these assumptions are not satisfied pose a number of tempting new problems. Some of these problems can be successfully solved without much ado. For instance, it is not difficult to allow for the effeet of collision inelasticity on the properties of pseudo-turbulent motion by means of replacing simple Equation 8.1 by other equations in which collisional energy dissipation is duly taken into account, as has been previously done in reference [25]. However, the repudiation of other assumptions is by no means a simple matter and requires a great deal of work. Fortunately, this work seems to be much facilitated by the mere fact that there exists a sound tentative model which plays the role of a certain initial approximation. It is the formulation of Just such a model that should be regarded as a main achievement of the present article. 

Besides elastic collisions, inelastic collisions may also occur in which the excitation energy Ei of atom A is either partly or completely transferred into internal energy of the collision partner B, or into translational energy of both partners. Such inelastic collisions are often called quenching collisions because they decrease the number of excited atoms in level Ei and therefore quench the fluorescence intensity. The total transition probabiltiy A/ for the depopulation of level Ei is a sum of radiative and collision-induced probabilities (Fig. 2.16)... 

In Sect.3.3, we saw that the spectral line profile is altered by two kinds of collisions. Inelastic collisions cause additional damping, resulting in pure broadening of the Lorentzian line profile. This broadening by inelastic collisions brings about a homogeneous Lorentzian line profile. 

The site specificity of reaction can also be a state-dependent site specificity, that is, molecules incident in different quantum states react more readily at different sites. This has recently been demonstrated by Kroes and co-workers for the Fl2/Cu(100) system [66]. Additionally, we can find reactivity dominated by certain sites, while inelastic collisions leading to changes in the rotational or vibrational states of the scattering molecules occur primarily at other sites. This spatial separation of the active site according to the change of state occurring (dissociation, vibrational excitation etc) is a very surface specific phenomenon. 

Marcus R A 1970 Extension of the WKB method to wave functions and transition probability amplitudes (S-matrix) for inelastic or reactive collisions Chem. Phys. Lett. 7 525-32... 

The fimdamental kinetic master equations for collisional energy redistribution follow the rules of the kinetic equations for all elementary reactions. Indeed an energy transfer process by inelastic collision, equation (A3.13.5). can be considered as a somewhat special reaction . The kinetic differential equations for these processes have been discussed in the general context of chapter A3.4 on gas kmetics. We discuss here some special aspects related to collisional energy transfer in reactive systems. The general master equation for relaxation and reaction is of the type [H, 12 and 13, 15, 25, 40, 4T ] ... 

Bodo E, Gianturco F A and Paesani F 2000 Testing intermolecular potentials with scattering experiments He-CO rotationally inelastic collisions Z. Phys. Chem., A/F214 1013-34... 

Steinfeld J I, Ruttenberg P, Millot G, Fanjoux G and Lavorel B 1991 Scaling laws for inelastic collision processes in diatomic molecules J. Phys. Chem. 95 9638—47... 

The differential cross section for inelastic collisions exciting the nth state of the target then takes the fomi... 

Figure Bl.24.4. Energy loss components for a projectile that scatters from depth t. The particle loses energy A E- via inelastic collisions with electrons along the inward path. There is energy loss A E in the elastic scattering process at depth t. There is energy lost to melastic collisions A along the outward path. For an incident energy Eq the energy of tlie exiting particle is = q - A iv - AE - A E. ...

SIMS Secondary Ion mass spectroscopy A beam of low-energy Ions Impinges on a surface, penetrates the sample and loses energy In a series of Inelastic collisions with the target atoms leading to emission of secondary Ions. Surface composition, reaction mechanism, depth profiles... 

This chapter deals with qnantal and semiclassical theory of heavy-particle and electron-atom collisions. Basic and nsefnl fonnnlae for cross sections, rates and associated quantities are presented. A consistent description of the mathematics and vocabnlary of scattering is provided. Topics covered inclnde collisions, rate coefficients, qnantal transition rates and cross sections. Bom cross sections, qnantal potential scattering, collisions between identical particles, qnantal inelastic heavy-particle collisions, electron-atom inelastic collisions, semiclassical inelastic scattering and long-range interactions. 

Inelastic scattering produces a pennanent change in the internal energy and angrilar momentum state of one or both structured collision partners A and B, which retain their original identity after tire collision. For inelastic = (a, P) — /= (a, P ) collisional transitions, tlie energy = 1 War 17 of relative motion, before ( ) and after... 

Both conventions are identical only for direct collisions A (a) + B((3) A(a )+B(P ). This nonnalization is customary [5] for elastic and inelastic scattering processes. 

A partial wave decomposition provides the frill close-coupling quantal method for treating A-B collisions, electron-atom, electron-ion or atom-molecule collisions. The method [15] is siumnarized here for the inelastic processes... 

For electronic transitions in electron-atom and heavy-particle collisions at high unpact energies, the major contribution to inelastic cross sections arises from scattering in the forward direction. The trajectories implicit in the action phases and set of coupled equations can be taken as rectilinear. The integral representation... 

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