Tóm tắt
Motion in many forms may be studied by light scattering. On one extreme this may be the bulk motion of a large target such as a vehicle or a satellite; on the other it may be the diffusional motion of an atom or molecule. The paper will outline the basic principles involved in such measurements and introduce the mathematical apparatus required to derive spectra of the scattered light. This can be couched in terms of speckle and Doppler shifts in the first case, while for molecular systems in thermodynamic equilibrium, we need a form of modern many-body theory. With this we calculate dynamical mode correlations as functions of the transport coefficients of irreversible thermodynamics. Examples will be given in the measurement of flow and turbulence, marcromolecular diffusion and polydispersity, and molecular scattering, including mode-mode coupling effects in condensed matter.
