Elasticity energy transfer

To evaluate quasi-elastic energy transfer from an electron gas to neutral molecules, the rotational excitation can be combined with the elastic collisions. The process is then characterized by a gas-kinetic rate coefficient cro( e) 3 10 cm /s (where (ne> is the average thermal velocity of electrons), and each collision is considered as a loss of about e ( ) of electron energy. 

NES is an elastic and coherent scattering process, i.e., it takes place without energy transfer to electronic or vibronic states and is delocalized over many nuclei. Owing to the temporal and spatial coherence of the radiation field in the sample. 

Electron beams Particle-matter interactions > (a) Inelastic interactions (energy transfer with sample species) SPECTROSCOPY (b) Elastic interactions (energy transfer) DIFFRACTION, MICROSCOPY... 

We say such a collision is elastic if no energy transfers during the collision between the gas particle and the mirror but if energy does transfer - and it usually does - we say the collision is inelastic. 

Excited states can be formed by a variety of processes, of which the important ones are photolysis (light absorption), impact of electrons or heavy particles (radiolysis), and, especially in the condensed phase, ion neutralization. To these may be added processes such as energy transfer, dissociation from super-excited and ionized states, thermal processes, and chemical reaction. Following Brocklehurst [14], it is instructive to consider some of the direct processes giving excited states and their respective inverses. Thus luminescence is the inverse of light absorption, super-elastic collision is the inverse of charged particle impact excitation, and collisional deactivation is the inverse of the thermal process, etc. 

Stationary) and the other is moving, and if its trajectory crosses the location of the other object, the energy of the moving object is distributed between the two. If the collision is perfectly elastic the energy remains with the moving ball—if it is inelastic some level of energy transfer will take place. We observe very similar type of events at the molecular level when photons collide with atoms or molecules. 

Figure 3.19. Variation of the energy transfer into the surface in scattering of NO from Ag(l 11) as a function of Ee = f ccsO,-. Solid lines and solid points are for rotationally elastic scattering. /, = Jj = 0.5 and the open points are for non-state-resolved scattering experiments (and therefore also contains a contribution from rotationally inelastic scattering). From Ref. [181].

The next n flowing units (segments or molecules) will also change their elastic potential due to one single molecular displacement so that the total energy transfer is given by A ei = n A.i ei,. The shift r0 is related to n flowing units and with the law of Hooke we can write... 

This elastic energy will be transformed into thermal energy, that is, we observe the stimulation of thermal vibrations. All flowing processes therefore constitute a transfer of elastic (or dielectric) energy into thermal energy. As we see in Fig. 13 between the direction of an external stress o and that of the possible motion of a flowing unit we have an angle distance between the minimum and the saddle point will be r0. The distance related to the direction of the stress o is r0 cos tp. Therefore we external force from B to B will be F = o cos ip. 

Figure 18. Energy-transfer spectrum for Na +N2. Energy transfer A vlb ro, is measured in units of vibrational quanta v after collision. Shaded area indicates strong superposition of elastic scattering processes. Horizontal bars illustrate experimental resolution. Kinematic deconvolution is indicated 0.

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