Download or read book Some Studies in Deconvoluting Coincidence Doppler Broadening Spectra written by King-Fung Ho and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Some Studies in Deconvoluting Coincidence Doppler Broadening Spectra" by King-fung, Ho, 何競豐, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled SOME STUDIES IN DECONVOLUTING COINCIDENCE DOPPLER BROADENING SPECTRA submitted by Ho King Fung for the degree of Master of Philosophy at the University of Hong Kong in August 2001 Recent years have seen a renewed interest in the technique of Coincidence Doppler Broadening Spectroscopy (CDBS) in which one dimensional electronic momenta in materials are studied by means of both gamma ray energies emitted in the process of positron annihilation. Advantages of CDBS over conventional positron Doppler spectroscopy are its 40% improved resolution and its much reduced background at high momenta. The present work capitalizes on the fact that CDBS row data is in the form of a 2D image, with excellent prospects for implementing deblurring algorithms for the removal of the instrumental error of measurement that arise from the availability of an accurate point spread function in the 85 reference gamma ray line of Sr at 514keV. The generalized least square method with Tikonov-Miller regularization is introduced by incorporating a priori information of non- negativity into the mathematical regularization technique for solution of operator equations. By means of Monte-Carlo method, the simulated observed function and instrumental function have been generated and deconvoluted so as to obtain the optimal regularization parameter, size of matrices, number of counts and choice of derivative for the norm. Under the current resources, spectra which are as large as 1024x1024 matrix size can be deconvoluted in a reasonable period of time. The resulting "constrained regularization" method is found to achieve both stable computations and good resolution levels. It is shown that successful deconvolution of CDBS data is a promising area of endeavour with the potential for producing momentum distributions of a quality comparable to those of the angular correlation technique but with significantly faster data accumulation rates. DOI: 10.5353/th_b2977372 Subjects: Laser spectroscopy Spectrum analysis - Deconvolution
Download or read book Some Studies in Deconvoluting Coincidence Doppler Broadening Spectra written by King-fung Ho and published by . This book was released on 2001 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Optimized Deconvoluted Coincidence Doppler Broadening Spectroscopy and Deep Level Transient Spectroscopies with Applications to Various Semiconductor Materials written by Jingdong Zhang and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Development of Optimized Deconvoluted Coincidence Doppler Broadening Spectroscopy and Deep Level Transient Spectroscopies With Applications to Various Semiconductor Materials" by Jingdong, Zhang, 張敬東, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled DEVELOPMENT OF OPTIMIZED DECONVOLUTED COINCIDENCE DOPPLER BROADENING SPECTROSCOPY AND DEEP LEVEL TRANSIENT SPECTROSCOPIES WITH APPLICATIONS TO VARIOUS SEMICONDUCTOR MATERIALS Submitted by Zhang Jing Dong for the degree of Doctor of Philosophy at The University of Hong Kong in September 2006 Both Positron Annihilation Spectroscopy (PAS) and Deep Level Spectroscopy (DLS) are techniques used to study defect structures in solids. The former is a non-destructive technique particularly useful for studying vacancy type defects in condensed matter. DLS, on the other hand, is an electrical characterization tool for investigating deep energy levels of defects inside the energy band gap of a semiconductor. In this thesis, the basic physics behind PAS and DLS was reviewed together with the various experimental set-ups required to implement them. A full description was provided of a newly constructed digital DLS spectrometer that can perform both DLTS (Deep Level Transient Spectroscopy) and DLOS (Deep Level Optical Spectroscopy). Coincidence Doppler Broadening Spectroscopy (CDBS) is one of the popular PAS techniques due to its ability to measure the high electron momentum components in bulk and defect states. At low momentum, however, it suffers from the problem of poor instrumental resolution. Various CDBS deconvolution algorithms have been investigated to enhance the resolution at low momentum. It was shown that the Richardson-Lucy (RL) algorithm gives CDBS deconvolution results approaching the quality of 1D angular correlation or annihilation radiation (ACAR) spectroscopy, with the advantages of retaining the high momentum components and requiring no complex tent function corrections. The RL-CDBS technique has been tested against theory and 1D-ACAR results for different metals and found to obtain slightly superior results than other existing algorithms while using far less computer resources. Major PAS studies have been carried out on bulk and 10MeV electron irradiated Si and 300keV and 1.5MeV SiC. For bulk Si, the different shapes of the low momentum densities for different directions have been well recovered using RL-CDBS. The different momentum distributions recovered for the Si-P monovacancy and the Si divacancy were shown to agree well with theoretical predictions. For the electron irradiated SiC the carbon vacancy V and the silicon vacancy V have been identified according to the electron energies and according to Si the high energy momentum components seen by CDBS. More complex semiconductor systems such electron irradiated GaN and hydrothermally grown ZnO have also been studied by RL-CDBS and Positron Lifetime Spectroscopy. Because GaN materials are widely used in opto-electronic industry the digitized DLS setup has been used to study the defect levels in electron irradiated GaN. For the CDBS and RL-CDBS studies on GaN, SiC and ZnO various methods of "fingerprinting" different defects such as "ratio curves," "difference curves" have been tested. The "autocorrelation function" method has also been used extensively and found to provide novel and useful information on the nature of defects. DOI: 10.5353/th_b3827901 Subjects: Deep level transient spectroscopy Positron annihilation Spectrum analysis - Deconvolution Se
Download or read book Development of Optimized Deconvoluted Coincidence Doppler Broadening Spectroscopy and Deep Level Transient Spectroscopies with Applications to Various Semiconductor Materials written by Jingdong Zhang and published by . This book was released on 2006 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Positron Annihilation in Semiconductors written by Reinhard Krause-Rehberg and published by Springer Science & Business Media. This book was released on 1999 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive book reports on recent investigations of lattice imperfections in semiconductors by means of positron annihilation. It reviews positron techniques, and describes the application of these techniques to various kinds of defects, such as vacancies, impurity vacancy complexes and dislocations.
Download or read book Study of Aluminum Using Coincidence Doppler Broadening Spectroscopy written by Nicholas Byrnes and published by . This book was released on 2018 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Positron Spectroscopy of Solids written by Società italiana di fisica and published by IOS Press. This book was released on 1995 with total page 807 pages. Available in PDF, EPUB and Kindle. Book excerpt: The lifetime of a positron inside a solid is normally less than a fraction of nanosecond. This is a very short time on a human scale, but is long enough to enable the positron to visit an extended region of the material, and to sense the atomic and electronic structure of the environment. Thus, we can inject a positron in a sample to draw from it some signal giving us information on the microscopic properties of the material. This idea has been successfully developed in a number of positron-based techniques of physical analysis, with resolution in energy, momentum, or position. The complex of these techniques is what we call now positron spectroscopy of solids. The field of application of the positron spectroscopy extends from advanced problems of solid-state physics to industrial applications in the area of characterization of high-tech materials. This volume focuses the attention on the physics that can be learned from positron-based methods, but also frames those methods in a wider context including other experimental approaches. It can be considered as a textbook on positron spectroscopy of solids, the sort of book that the newcomer takes for his approach to this field, but also as a useful research tool for the expert.
Download or read book Positron Beams and Their Applications written by Paul G. Coleman and published by World Scientific. This book was released on 2000 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a coherent and comprehensive overview of the generation and application of mono-energetic positron beams. It has been written by acknowledged experts, at a level accessible to graduate students working, or planning to work, with positron beams, and to scientists in other areas who want to know something about the field.The book begins with a brief historical introduction and an overview of how positron beams are generated and transported. A description of the fate of slow positrons in gaseous and condensed matter, with reference to many of the fundamental measurements made possible by the advent of positron beams, is followed by a discussion on applications in the study of solid surfaces, defect profiling in subsurface regions, interfaces and thin films, and the probing of bulk properties in novel ways. The book ends with a look at the future, considering the prospects for intense positron beams and their potential for further research.
Download or read book Book of Abstracts from the International Workshop on Positron Studies of Defects 2024 PSD 24 written by Rafael Ferragut and published by Trans Tech Publications Ltd. This book was released on 2024-08-23 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following the long tradition that started in 1987, the International Workshop on Positron Studies of Defects 2024 (PSD-24) will be held in Como, Italy, in the period from September the 1st to 6th, 2024. The aim of the workshop is to provide an opportunity for exchange of the latest results and scientific information concerning the positron interactions with solids and surfaces, the generation of slow positron beams and their applications.
Download or read book The Doppler Effect written by Thomas Perrott Gill and published by Academic Press. This book was released on 1965 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quasicrystals written by Hans-Rainer Trebin and published by John Wiley & Sons. This book was released on 2006-05-12 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quasicrystals form a new state of solid matter beside the crystalline and the amorphous. The positions of the atoms are ordered, but with noncrystallographic rotational symmetries and in a nonperiodic way. The new structure induces unusual physical properties, promising interesting applications. This book provides a comprehensive and up-to-date review and presents most recent research results, achieved by a collaboration of physicists, chemists, material scientists and mathematicians within the Priority Programme "Quasicrystals: Structure and Physical Properties" of the Deutsche Forschungsgemeinschaft (DFG). Starting from metallurgy, synthesis and characterization, the authors carry on with structure and mathematical modelling. On this basis electronic, magnetic, thermal, dynamic and mechanical properties are dealt with and finally surfaces and thin films.
Download or read book Neutron Scattering and Other Nuclear Techniques for Hydrogen in Materials written by Helmut Fritzsche and published by Springer. This book was released on 2016-04-22 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of the main nuclear characterization techniques used to study hydrogen absorption and desorption in materials. The various techniques (neutron scattering, nuclear magnetic resonance, ion-beams, positron annihilation spectroscopy) are explained in detail, and a variety of examples of recent research projects are given to show the unique advantage of these techniques to study hydrogen in materials. Most of these nuclear techniques require very specialized instrumentation, and there are only a handful of these instruments available worldwide. Therefore, the aim of this book is to reach out to a readership with a very diverse background in the physical sciences and engineering and a broad range of hydrogen-related research interests. The same technique can be used by researchers interested in the improvement of the performance of hydrogen storage materials and by those focused on hydrogen ingress causing embrittlement of metals. The emphasis of this book is to provide tutorial material on how to use nuclear characterization techniques for the investigation of hydrogen in materials – information that cannot readily be found in conference and regular research papers. Provides a comprehensive overview of nuclear techniques used for hydrogen-related research Explains all nuclear techniques in detail for the non-expert Covers the whole range of hydrogen-related research Features chapters written by world-renowned experts in nuclear technique and hydrogen-related research
Download or read book Positrons in Solids written by P. Hautojärvi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: In condensed matter initially fast positrons annihilate after having reached equi librium with the surroundings. The interaction of positrons with matter is governed by the laws of ordinary quantum mechanics. Field theory and antiparticle properties enter only in the annihilation process leading to the emergence of energetic photons. The monitoring of annihilation radiation by nuclear spectroscopic methods provides valuable information on the electron-positron system which can directly be related to the electronic structure of the medium. Since the positron is a positive electron its behavior in matter is especially interesting to solid-state and atomic physi cists. The small mass quarantees that the positron is really a quantum mechanical particle and completely different from any other particles and atoms. Positron physics started about 25 years ago but discoveries of new features in its interac tion with matter have maintained continuous interest and increasing activity in the field. Nowadays it is becoming part of the "stock-in-trade" of experimental physics.
Download or read book Principles of Plasma Spectroscopy written by Hans R. Griem and published by . This book was released on 1997 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a comprehensive description of the theoretical foundations and experimental applications of spectroscopic methods in plasma physics research. It introduces the classical and quantum theory of radiation, with detailed descriptions of line strengths and high density effects, and describes theoretical and experimental aspects of spectral line broadening. The book illustrates the concepts of continuous spectra, level kinetics and cross sections, thermodynamic equilibrium relations, radiative energy transfer, and radiative energy losses. The basics of plasma spectroscopy to density and temperature measurements and to the determination of some other plasma properties are also explored. Over one thousand references not only guide the reader to original research covered in the chapters, but also to experimental details and instrumentation.
Download or read book Instrumental and Doppler Broadening in the Fabry perot Interference Pattern of Close Doublets written by P. M. Griffin and published by . This book was released on 1949 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Techniques In Physics And Materials Sciences Principles And Methodologies written by R Srinivasan and published by World Scientific. This book was released on 2023-10-12 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: There have been new developments in experimental techniques for preparing and characterizing materials and for measuring their properties. These techniques are not being taught to students at the master's or even doctoral levels because there is no single book which deals with all these techniques at a basic level. The present book is an attempt to overcome this problem.The book is divided into five sections: (1) Techniques for preparing materials in the bulk, nanoscale and thin film forms; (2) Techniques for characterizing materials like X ray and neutron powder diffraction, ESCA, Ellipsometry for thin films, Ultrasonic techniques, Electron microscopy, Surface probe techniques and Positron annihilation for defect studies; (3) Techniques for measurements, at research level, of the elastic, thermal, electrical, dielectric and magnetic properties; (4) Spectroscopic techniques such as NMR-EPR spectroscopy, IR, Visible-UV spectroscopy and Mossbauer spectroscopy and (5) Phase transitions. In each of the above topics the basic principles are clearly laid out, the experimental set-ups are described, and typical examples are cited to illustrate the physics revealed by these techniques.The book can be used for a two-semester course on experimental techniques in physics and materials science at the master's and pre-doctoral degree levels for students.
Download or read book New Topics in Superconductivity Research written by Barry P. Martins and published by Nova Publishers. This book was released on 2006 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconductivity is the ability of certain materials to conduct electrical current with no resistance and extremely low losses. High temperature superconductors, such as La2-xSrxCuOx (Tc=40K) and YBa2Cu3O7-x (Tc=90K), were discovered in 1987 and have been actively studied since. In spite of an intense, world-wide, research effort during this time, a complete understanding of the copper oxide (cuprate) materials is still lacking. Many fundamental questions are unanswered, particularly the mechanism by which high-Tc superconductivity occurs. More broadly, the cuprates are in a class of solids with strong electron-electron interactions. An understanding of such "strongly correlated" solids is perhaps the major unsolved problem of condensed matter physics with over ten thousand researchers working on this topic. High-Tc superconductors also have significant potential for applications in technologies ranging from electric power generation and transmission to digital electronics. This ability to carry large amounts of current can be applied to electric power devices such as motors and generators, and to electricity transmission in power lines. For example, superconductors can carry as much as 100 times the amount of electricity of ordinary copper or aluminium wires of the same size. Many universities, research institutes and companies are working to develop high-Tc superconductivity applications and considerable progress has been made. This volume brings together new leading-edge research in the field.
