摘要:

This article surveys what has happened in the last 25 years in the field of electronic properties of non-crystalline materials, particularly semiconductors. The problem, as it appeared 15 years ago, of the energy gap in a non-crystalline material is described, as is the role of Anderson's concept of localization. Emphasis is given to recent work in many laboratories on hydrogenated amorphous silicon, on the life-time of carriers and on defects of dangling bond type. Some of the questions at present unresolved are mentioned, particularly the sign of the Hall effect, and the part played by long-range fluctuations of potential. The concept of valence alternation pairs in the chalcogenide glasses is described. A final section gives a very brief outline of developments in the last few years in our understanding of ‘metallic’ conduction, when the mean free path is very short, whether in amorphous metals or heavily doped semiconductors.

ISSN:0010-7514    

DOI:10.1080/00107518508223682

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The great majority of experiments in particle physics use beams of particles from accelerators. Individual interactions of these with other particles are observed by detector systems. Fixed target and colliding beam experiments are contrasted, and non-accelerator experiments mentioned briefly. An account is given of the principles of the various detectors. These include scintillation and Cerenkov counters and the various tracking devices such as bubble chambers, proportional and drift chambers. Calorimeters have emerged recently as important detectors at the highest energies. Electronic logic modules are mentioned and the main steps in data acquisition and analysis are described. Finally an example is given of a large detector system.

ISSN:0010-7514    

DOI:10.1080/00107518508223683

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Charged particles can be confined by electromagnetic fields to a finite volume in space for extended periods of time. The extremely long observation time along with the nearly perturbation-free environment under ultra-high vacuum conditions opens new regions of spectroscopy, which are not accessible by other methods. In microwave spectroscopy resonance lines as narrow as Δv/v = 3 × 10−12have been obtained, which leads directly to the possible development of a new type of frequency standard. Lifetimes of metastable levels in the region of many seconds can be observed, as well as rare collision processes between ions and molecules, which are important for the formation of larger molecules in interstellar space. Finally, phenomena like crystallisation in a non-neutral plasma may be investigated at sub-Kelvin temperafures. accessible by the new technique of laser cooling of ions.

ISSN:0010-7514    

DOI:10.1080/00107518508223684

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A review is presented of two of the many topical areas of interest in two-dimensional transport in silicon inversion layers. The first topic is localization: strong localization in a band tail, and quantum interference and the possible localization of all states in two dimensions. The second topic is the quantum Hall effect which is a manifestation of localization in a strong magnetic field.

ISSN:0010-7514    

DOI:10.1080/00107518508223685

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518508223686

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518508223687

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Third Workshop on Grand Unification, University of North Carolina, April 1982. Edited by P. H. Frampton, S. C. Glashon and H. Van Dam. (Boston: Birkhäuser, 1982.) [Pp.ix + 371.] Scope: Conference proceedings. Level Specialist post-graduate.

ISSN:0010-7514    

DOI:10.1080/00107518508223688

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518508223689

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor