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The second quantization for many-body systems is introduced. Within this formalism an elementary derivation of a non-Markovian quantum kinetic equation is given for the reduced density matrix. Next we review the equilibrium Green functions, including the dissipation-fluctuation theorem, the self-energy concept, and the perturbation expansion. [ABSTRACT FROM AUTHOR]

Various concepts for the numerical solution of the semiclassical Boltzmann equation are discussed, including an illustration of the use of a linearized Boltzmann equation and its eigenfunction expansion for a 2D electron gas. The numerical results for the linearized Boltzmann equation are compared with those of an ensemble Monte Carlo simulation of the Master equation. Finally the Boltzmann equation together with the Poisson equation is solved self-consistently for a spatially inhomogeneous electron gas in the relaxation time approximation. [ABSTRACT FROM AUTHOR]

We review some of the general properties of the semiclassical Boltzmann equation - not necessarily restricting ourselves to the dilute electron gas - paying special attention to its irreversible properties. [ABSTRACT FROM AUTHOR]

Several optical configurations for signal processing have been discussed. The ability to format the input signals to enhance the processing ability of the optical system has been emphasized together with the importance of the input transducer. Specific attention has been given to the use of the folded spectrum for high time-bandwidth signal processing and to the use of coherent optical techniques in radar signal processing. From a simple description of the relation between the input raster format and output folded spectrum and selected examples of the use of this system, the potential of this powerful technique should be apparent. The extensive use of the DKDP light valve in radar signal processing has also been summarized in such a manner that the basic input format was identical in all instances. Extensions of these techniques in radar and other signal processing applications to include matched filter correlation are the subject of current research. In several years these two systems promise to have major impact on signal processing since they utilize the real-time, parallel processing, high time-bandwidth, and correlation properties of a coherent optical processor. [ABSTRACT FROM AUTHOR]

This chapter reviews the applications of coherent optical correlation techniques to the measurement of parallax from stereo-photographs. A brief description of the various coherent optical correlation techniques is presented and their relative merits outlined. Two experimental prototype systems are discussed in detail and their test evaluation results are presented. The potentials of coherent optical processing techniques have been demonstrated and evaluated using real world aerial transparencies. It is reasonable to expect the widespread use of coherent optical processing techniques in different facets of photogrammetric data reduction. [ABSTRACT FROM AUTHOR]

This chapter has presented a brief review of optical image processing and some of its applications. The references presented here are only a sample of a copious source of available information in this field. It is recommended that the reader maintain an awareness of current literature because of the continuous developments being reported. Optical data processing is in its early stages of utility. Present demonstrations of optical processing are essentially one-of-a kind illustrations of feasibility. The authors believe that full utility of optical processing will be realized with the development of necessary peripherals for interfacing to digital control systems. The incoherent to coherent transducer with a laser beam recorder is one significant peripheral that, when fully developed, will permit practical use of the optical processor. Data throughput rates for some processing applications may then be increased significantly. On this basis, optical processing technology should be emphasized in the coming years. [ABSTRACT FROM AUTHOR]

This particular chapter is probably somewhat unusual because its purpose is a little different than some of the other contributions. We are not looking at how optical methods are being used to solve problems in a particular field even though there is a continued activity in the area of optical analogs to X-ray diffraction. The thesis has really been that there have been interesting pieces of work carried out by researchers actively engaged in optical analog techniques that can provide considerable insight to those working in the various aspects of diffraction and optical processing. I trust that this proves to be true. [ABSTRACT FROM AUTHOR]

We hope that the capsule remarks included on the Fourier transform, holography, interferometry, and correlation will serve as an adequate reference base for the succeeding chapters. The application areas selected are the major ones in which optical data processing has made and promises to make significant contributions. [ABSTRACT FROM AUTHOR]

In this paper a brief review is given of the basic theoretical concepts concerning the explanation of some of the recent experiments in superfluid 3He below 3 mK. In section 2 the experimental results for the phase diagram of the A- and B-phases, the shifts of the transverse and longitudinal resonance frequencies, and the specific heat jumps are discussed. Section 3 deals with the properties of the anisotropic BCS-states which are used to describe the A- and B-phases, i.e., the Anderson-Morel (AM) and the Balian-Werthamer (BW) state, respectively. In section 4 the origin of the strongly pressure dependent spin-fluctuations and their effect on the relative stability of the AM- and BW-states, the specific heat jumps, and the NMR-frequency-shifts is discussed. The main section 5 contains a description of the couplings between the fluctuations of the spin and the order parameter for triplet-pairing and the resulting effect, in particular, on the pressure dependence of the specific heat jump. Section 6 stresses the fundamental role the dipole interactions, together with the order parameter fluctuations, play in generating spin waves of a finite energy gap and thus longitudinal, NMR-resonance. [ABSTRACT FROM AUTHOR]

The positron annihilation method and its experimental techniques are reviewed. With these techniques information is obtained about electron states in perfect crystals and about defects in real metals. The advantage of the positron annihilation method is outlined for the investigation of Fermi surfaces in disordered metal systems. The sensitivity of the technique for single vacancies and defect clusters is demonstrated with recent results on various metals. Vacancy formation energies can be obtained with high accuracy. In addition to the concentration of defects, information is obtained about the type of these defect centers. This opens new possibilities in annealing studies of irradiated metals to decide between various recovery models. [ABSTRACT FROM AUTHOR]

Principles of field-effect transistors and their various types are reviewed. Their physical properties are surveyed, and a brief outline of present device technology is given. [ABSTRACT FROM AUTHOR]

The conductivity of solid ionic conductors is determined by the concentration of the mobile ions and their mobilities. Both properties have a natural upper limit for solid electrolytes. The upper limit of the concentration is reached if all ions of one species are mobile and the upper limit of the mobility is reached if the activation energy for motion of the ions is practically zero i. e. that they move with thermal velocity between neighbouring lattice sites. Good solid electrolytes reach these limits or come close to them. Important solid electrolytes such as AgI, RbAg4I5, β-alumina, doped ZrO2 and CaF2 are discussed in detail. Galvanic solid state cells, which are of technical as well as scientific importance, can be constructed using solid ion conductors. The properties of these cells, their technical applications (e. g. in oxygen sensors, high temperature fuel cells, batteries and chemotronic building units) and their scientific applications for thermodynamic and kinetic investigations are discussed. [ABSTRACT FROM AUTHOR]

Initially, the milestones in material and device technology based on silicon are used to explain the various trends in this most important sector of electronics. Emphasis is put on the state of the art in large-scale operating hyperpure polycrystalline rods as well as float-zoned and crucible-pulled single crystals. Further production stages ending with polished slices and epitaxial layers also are considered in this survey. Economical aspects are discussed finally in the light of fruitful interaction between device manufacturers and materials producers. [ABSTRACT FROM AUTHOR]

This is an introduction into the physics, problems properties, and applications of stoichiometric laser materials. They can store several kilojoules of energy per cm3 for times ranging from 100 ns to 10 ms. Continuous room temperature laser operation can be achieved with just a few hundred microwatts of pump power. Optical gains up to 10 dB per optical wavelength can be expected. The physics involved in stoichiometric systems is described and related to spectroscopic properties. Threshold, pump power, and dynamical behavior (relaxation oscillations) are calculated including the effects of anisotropy, saturation, inversion profile, reabsorption, pump profile, and mode profile—effects that are important for materials with a high concentration of active ions. Structural aspects such as phase transitions, ferroelasticity, ionic spacings, probability density of rare earth electrons, and energy transfer are discussed using NdP5O14 as an example. Hybrid exchange is proposed as a possible mechanism for energy transfer between rare earth ions. Their wavefunctions overlap appreciably in stoichiometric materials. Examples are given of existing materials and of their applications. [ABSTRACT FROM AUTHOR]

Lead chalcogenides are direct semiconductors with small energy gap (ΔE≲0.3 eV) and therefore useful materials for optoelectronic devices in the infrared spectral region. Here we will discuss their use as laser diodes emitting between 2 and 20 μm. The state of crystal growth techniques and diode technology is reviewed in respect to low threshold current densities, high temperature operation in cw and pulsed mode and power output. Tuning of the emitted wavelength by temperature, hydrostatic pressure and magnetic fields is dealt with in detail. The applications of such diodes in gas spectroscopy are summarized. [ABSTRACT FROM AUTHOR]

Optical spectroscopy provides an excellent tool for the investigation of the electronic structure of matter. The optical properties of solids, liquids and gases are usually described either in an atomic or molecular (real space) picture or in a solid state bank (k-space) picture. Through the application of synchrotron radiation for optical measurements a radiation source has become available in the vacuum ultraviolet and soft X-ray region where both pictures are needed for an appropriate description of the optical properties of solids. In this broad photon energy range a great number of subshells in different atoms can be excited and the role of density of states, matrix elements, short range and long range order, correlation analysis by X-ray diffraction in crystallographic systems and many other applications have become possible by the use of synchrotron radiation. [ABSTRACT FROM AUTHOR]

In the early days of Brillouin scattering the range of possible experiments was severely limited by the inadequacy of the available instrumentation. With the development of the very high contrast multipass interferometer it is now possible to perform measurements on very small and imperfect crystals and even on opaque materials where the penetration depth of the light is as low as a few wavelengths. The wealth of phonon information that can be derived from Brillouin scattering experiments is discussed and illustrated with examples of measurements on layer compounds, opaque semiconductors, liquid crystals and materials undergoing structural phase transitions. Brillouin scattering occurs not only from phonons but also from spin waves in magnetic systems. Recent spin wave measurements on YIG and CrBr3 are discussed. [ABSTRACT FROM AUTHOR]

We present a comprehensive theory for impurity states in semiconductors. We find that when "true" impurity potentials are employed, the effective-mass theory is valid only for substitutional impurities whose core is isoelectronic to the host-atom core (isocoric impurities) independently of whether the resulting level, is shallow or relatively deep. By formulating the problem in terms of pseudopotential theory we obtain a more general theory which is valid for non-isocoric impurities as well, and in, fact reduces to the "true"-potential formalism in the case of isocoric impurities. We are thus able to directly predict binding energies for a variety of shallow and deep impurities. The theory also supplies new physical understanding of the effectivemass concept and of the mechanisms that determine the binding energies of impurities. Finally, we discuss impurity-like localized states in semiconductors. [ABSTRACT FROM AUTHOR]

We review some of the current work on the atomic and electronic structure of reconstructed (111) surfaces of group IV semiconductors. The reasons and the possible mechanisms that lead to formation of superstructures are discussed. Charge and spin density waves that follow from the electronic instability of a model ideal surface are considered in some detail. The closely analogous problem of superlattices in layered transition-metal dichalcogenides such as 1T-TaS2 is also briefly touched. [ABSTRACT FROM AUTHOR]

After a quick sketch of activities in the area of dc conductivity studies on semiconductor surface space charge layers, the paper presents a comprehensive summary of the high frequency, dynamical studies. We discuss in succession microwave frequency measurements of the parallel conductivity, the far-infrared resonance spectroscopy between electric subbands of the space charge layer and cyclotron resonance. In a concluding section we present some results on photoconductivity experiments and a discussion of some other possible resonance effects. [ABSTRACT FROM AUTHOR]

Electric subbands in n-type silicon inversion layers and their dependence on high magnetic fields are briefly reviewed. The information, which may be obtained by analyzing surface quantum oscillations of the Shubnikov-de Haas type is discussed. After a report of new data on effective masses and the g-factor of electrons in inversion layers with (110) and (111) orientation quantum transport data for p-type inversion layers on (110), (111) and (100) planes are reviewed. Recent self-consistent calculations of electric subbands and effective masses for p-type silicon inversion layers have shown, that the band structure is substantially changed by the surface electric field, and that the spin degeneracy is removed. The agreement between the calculated and measured heavy hole masses is satisfying. Finally, the experimental hole mobilities for the three main orientations are correlated with the theoretical calculations. [ABSTRACT FROM AUTHOR]

New effects associated with the quantization of confined carrier motion in ultrathin semiconductor heterostructures have recently been observed. Optical and electrical studies of molecular-beam grown AlxGa1−xAs-GaAs structures consisting of to 100 layers with layers as thin as 10 Å have revealed discrete structures which are difficelt to analyze with usual bulk crystal methods. A complete understanding can be achieved with simple one-dimensional quantum mechanical models. In particular, the analysis of the optical data gives detailed quantitative information about confined electrons, light and heavy holes, and excitons in the GaAs layers. The relevance of these results from band structure analysis to device technology will be considered. [ABSTRACT FROM AUTHOR]

For III-V semiconductors liquid-phase epitaxy (LPE) has become a useful process to produce both high-purity crystals and multilayer structures for practical applications. Firstly the basic principles of LPE are reviewed. The the experimental technique and the growth of high-purity layers are described. The incorporation of impurities during LPE is often a process far from thermodynamic equilibrium. Several factors causing departure from equilibrium are described. Macroscopic growth kinetics, the Schottky-barrier of the liquid metal-semiconductor system and the adsorption of impurities at the growing interface. [ABSTRACT FROM AUTHOR]

For reasons of economy and physics, superconducting magnets are being used increasingly in high energy physics. These magnets differ considerably from conventional iron magnets because the generation of magnetic fields by current distributions as well as the properties of conductor, reinforcing coil structures, and refrigeration require novel design philosophies and technological processes. Central fields of application are the big particle detectors such as bubble chambers or spark chambers and beam lines with time-constant or pulsed magnets. [ABSTRACT FROM AUTHOR]

A review is given on the energy levels, the generation and recombination, the transport and the trap kinetics of electrons and holes in organic molecular crystals with van der Waals bonds. Convincing experimental results are discussed which have led to basic aspects for a theoretical understanding. In this connection photoemission, injection, recombination-luminescence and the importance of space-charges are treated, whereas conduction in organic liquids, in polymers, in charge-transfer complexes and in radical ion salts is only briefly touched. [ABSTRACT FROM AUTHOR]

A survey of physical properties of ternary IB-III-VI2 and IIB-IV-V2 chalcopyrite semiconductors is presented. Crystal structure, phonon spectra, and electronic band structure are discussed, thereby stressing and exploiting the close relationship of these compounds to the IIB-IV, and III-V zinc blende semiconductors. The discussion also includes magnetic resonance investigations. The potential of chalcopyrite compounds for optoelectronic and nonlinear optical devices is emphasized. [ABSTRACT FROM AUTHOR]

Recent experiments on pseudo-one-dimensional conducting systems are reviewed. Diffuse X-ray and neutron-scattering experiments on the metal-organic compound K2Pt(CN)4Br0.3·3H2O are emphasized. These experiments support the idea that the metalinsulator transition is caused by a Kohn-Peierls instability due to the strong electron-phonon coupling in one dimension. The experimental evidence for the transition to 3-dimensional order at low temperatures is discussed, and limitations of current theoretical models are pointed out. Experiments on the organic charge transfer salt TTF-TCNQ are discussed which support the general picture of the physics of one-dimensional conductors emerging from the scattering studies. In relation to the experimental results, the present view of the Fröhlich collective mode conductivity is summarized. [ABSTRACT FROM AUTHOR]

Changes in several solid state properties are expected when moving from the bulk crystal to small particles. The fundamental problems of the electronic band structure and the lattice vibration spectrum of particles having only 102 to 104 atoms are still in the beginning theoretical stages. Various anomalies should occur if the mean electronic level spacing exceeds thermal or photon or magnetic excitations. The recent widespread interest on surface excitations (surface phonons and plasmons) in small particles arises from the possibilities of observing the effects with infrared absorption and Raman and neutron scattering. [ABSTRACT FROM AUTHOR]

Conversion of sunlight into electrical energy by the use of solar cells is by far the most important method of power supply for satellites. The physical principles underlying the photovoltaic energy conversion are briefly outlined. Performance characteristics of solar cells like conversion efficiency are derived from material data. Principle and technological necessary power loss factors are presented. The state-of-the-art of the present solar cell technology and recent developments are elucidated. Economical aspects are discussed especially concerning a possible application of photovoltaic energy conversion for terrestrial power supply. [ABSTRACT FROM AUTHOR]