Generalized kinetic and evolution equations in the approach of the nonequilibrium statistical operator

The method of the nonequilibrium statistical operator developed by D. N. Zubarev is employed to analyse and derive generalized transport and kinetic equations. The degrees of freedom in solids can often be represented as a few interacting subsystems (electrons, spins, phonons, nuclear spins, etc.). Perturbation of one subsystem may produce a nonequilibrium state which is then relaxed to an equilibrium state due to the interaction between particles or with a thermal bath. The generalized kinetic equations were derived for a system weakly coupled to a thermal bath to elucidate the nature of transport and relaxation processes. It was shown that the "collision term" had the same functional form as for the generalized kinetic equations for the system with small interactions among particles. The applicability of the general formalism to physically relevant situations is investigated. It is shown that some known generalized kinetic equations (e.g. kinetic equation for magnons, Peierls equation for phonons) naturally emerges within the NSO formalism. The relaxation of a small dynamic subsystem in contact with a thermal bath is considered on the basis of the derived equations. The Schrodinger-type equation for the average amplitude describing the energy shift and damping of a particle in a thermal bath and the coupled kinetic equation describing the dynamic and statistical aspects of the motion are derived and analysed. The equations derived can help in the understanding of the origin of irreversible behavior in quantum phenomena.Comment: 21 pages, Revte

Statistical Theory of Spin Relaxation and Diffusion in Solids

A comprehensive theoretical description is given for the spin relaxation and diffusion in solids. The formulation is made in a general statistical-mechanical way. The method of the nonequilibrium statistical operator (NSO) developed by D. N. Zubarev is employed to analyze a relaxation dynamics of a spin subsystem. Perturbation of this subsystem in solids may produce a nonequilibrium state which is then relaxed to an equilibrium state due to the interaction between the particles or with a thermal bath (lattice). The generalized kinetic equations were derived previously for a system weakly coupled to a thermal bath to elucidate the nature of transport and relaxation processes. In this paper, these results are used to describe the relaxation and diffusion of nuclear spins in solids. The aim is to formulate a successive and coherent microscopic description of the nuclear magnetic relaxation and diffusion in solids. The nuclear spin-lattice relaxation is considered and the Gorter relation is derived. As an example, a theory of spin diffusion of the nuclear magnetic moment in dilute alloys (like Cu-Mn) is developed. It is shown that due to the dipolar interaction between host nuclear spins and impurity spins, a nonuniform distribution in the host nuclear spin system will occur and consequently the macroscopic relaxation time will be strongly determined by the spin diffusion. The explicit expressions for the relaxation time in certain physically relevant cases are given.Comment: 41 pages, 119 Refs. Corrected typos, added reference

Sur la nouvelle méthode pour la détermination des diamètres angulaires des étoiles au moyen de la lumière elliptiquement polarisée

Pokrowsky . Sur la nouvelle méthode pour la détermination des diamètres angulaires des étoiles au moyen de la lumière elliptiquement polarisée. In: Bulletin astronomique, tome 29, 1912. pp. 305-318

Hole burning spectroscopy of R′ aggregate color centers in polycrystalline LiF thin films using a GaAlAs diode laser

The first spectroscopic measurements of R′ aggregate color centers contained in polycrystalline LiF hosts are reported. The inhomogeneous and homogeneous widths of the 830-nm zero phonon line are measured by conventional grating spectroscopy and by photochemical hole burning spectroscopy using a current tuned GaAlAs diode laser with 3-mW output power. An extensive photochemical hole burning comparison between single and polycrystalline samples is presented.Peer Reviewe

Spectroscopic characteristics of the R' color center aggregate in LiF

The spectroscopic characteristics of the 833 nm zero phonon transition of the R' aggregate color center are studied both in single crystal and in polycrystalline LiF. Both the homogeneous and inhomogeneous linewidths are found to depend on the irradiation method and on the crystalline structure. © 1984.Peer Reviewe