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|Type:||Artigo de periódico|
|Title:||Nonequilibrium Thermodynamics And Quasielastic Light Scattering From Crystals|
|Abstract:||A methodology is proposed whereby a systematic analysis may be carried out of the spectrum of light scattered quasielastically by crystals. It involves: (i) determination of the equations satisfied by the crystal's thermodynamic variables, taking into account irreversible processes of energy dissipation, (ii) solution of such equations for the chosen scattering vector and the relevant crystalline symmetry, and (iii) determination of the spectrum by means of the Onsager hypothesis relating the solutions obtained and the correlation functions involving the same variables. The methodology was applied to KH2PO4 and to the superionic conductor RbAg4I5. The degrees of freedom associated with the diffusing silver ions in RbAg4I5 were assumed to be characterized by an internal (strain-independent) temperature and taken into account by means of a relaxing internal specific heat, the relaxation time being related to the hopping frequency. As the temperature is lowered, the ionic conductivity decreases, with a consequent decrease in the relaxation frequency and thus an increase in the Rayleigh intensity, typical of "central-peak behavior," is predicted. © 1979 The American Physical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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