This volume examines a timely problem in solid state physics, the condensation of ex- citons in semiconductors. The papers in this volume describe a new approach to the study of exciton condensation based on microwave-frequency conductivity and the breakdown of an ex- citon gas in a microwave field, an effect discovered by the authors. These methods have been used in extensive studies of germanium and have produced important new data about the con- densation process. In addition to the experimental data, a theory is presented for the micro- wave breakdown of excitons in the presence of...

This volume, which comprises a collection of papers by leading Soviet researchers, is devoted to topics in the luminescence of semiconductors. An experimental check is made on a series of predictions of the theory of ionization domains. A new low-voltage luminescence of zinc sulfide is described and investigated and is found to be due to a high-frequency electrical instability. A detailed study of the electrical properties of the instability and of the characteristics of the emission testifies to the pre-breakdown character of the electroluminescence and to the acousto electrical nature of...

This collection contains survey articles dealing with the following topics: The Mach principle and its role in the general theory of relativity, the modern conception of the vacuum, new methods in the theory of Lie group representations, the coherent state method and its applica- tion to physical problems, and the Newman-Penrose method and its application to problems in general relativity theory. v CONTENTS On the Problem of Singularity in the De Sitter Model . . . . . . . . . . . . . . . . . . . . . . . . . . 1 v. K. Mal'tsev and M. A. Markov On the Integral Formulation of the Mach Principle...

This volume reports investigations which form part of a major series of theoretical and experimental studies being carried out in the Laboratory of Low-Temperature Plasma Optics at the Lebedev Physics Institute in Moscow. The papers give the results of systematic investigations of the chemical composition and of the electrical and optical properties of dis- charge plasmas, and also of populations of laser levels. Reliable and detailed information is given on the dissociation of carbon dioxide gas in discharges; the nature of the velocity dis- tribution function, average energies, and...

The principal results of the work are as follows: 1. A simplified technique was devised for obtaining Raman spectra of powders. 2. The Raman and infrared absorption spectra of the following oxides were investigated: AsP3' SbP3' As 0 - SbP5. Te02. Ge02 (two forms) in the crystalline state, and ASP3' Ge02' Te0 in the glassy state. 2 5 2 3. The vibrational spectra of the crystalline and glassy forms of the oxides ASP3' Ge02' Te02 are simi- lar in many main respects, indicating a similarity of their structural units which determine the vibrational spec- tra of these substances. 4. By a study of...

This anthology includes articles on experimental studies of the interaction of high-power electromag- netic waves with collisionless plasmas and with electrons. The nonlinear interaction of waves with plasmas has been investigated both under free space conditions and in waveguides. A study of secondary-emission dis- charges was made in order to ascertain their possible effect on measurements in waveguides. The results presented here on the interaction of high-power waves with plasmas and electrons are of interest to a wide range of physicists and engineers concerned with various questions on...