Collision small-angle

Consider for a moment a rod-shaped particle of unit length. The orientation of the rod, u, can be specified by a unit vector u directed along its axis with spherical polar coordinates, D - id, random walk along the surface of the unit sphere. Debye [16] in 1929 developed a model for the reorientation process based on the assumption that collisions are so fiiequent that a particle can rotate throu only a very small angle before having another reorienting collision (i.e., small step diffusion). Debye began with the diffusion equation... 

Care must be taken in designing the collision apparatus and electron detector (normally a Faraday cup or retarding field analyser) to ensure that equation (2.9) is applicable and small-angle scattering is eliminated (Wagenaar and de Heer, 1985 Bederson and Kieffer, 1971). To allow for... 

Decoherence theory explains that a quantum object may loose some of its particular quantum properties due to the interaction with its environment. This phenomenon is investigated along two fines. First the authors study the influence of small angle collisions exerted by a dilute thermal gas on the molecules in the interferometer. They also focus on a novel property which is unique to large objects with many internal degrees of freedom, namely the thermal emission of photons. If sufficiently many photons of sufficiently short wavelength... 

There are two small parameters in Eq. (10.42), (n - T ) and Up /a. The first or the second term can predominate in Eq. (10.42). The bubble buoyancy cannot be sensitive to the existence of f s.fz., not even at very small angle rt - T. In Section 8.7.3 this was proven for small Re. The coincidence of the measured bubble velocity with that calculated for a solid sphere is not the ground to calculate the collision efficiency neglecting the mobility of the bubble surface. Its influence can predominate according Eq. (10.2.23). 

Debye (1929) developed a model for the reorientation processes based on the assumption that collisions are so frequent in a liquid that a molecule can only rotate through a very small angle before suffering a reorienting collision (small-step diffusion). We give here a heuristic treatment of the Debye model. 

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