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Development And Optimization Of A Positron Annihilation Lifetime Spectrometer To Measure Nanoscale Defects In Solids And Borane Cage Molecules In Aqueous Nitrate Solutions
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Book Synopsis Development and Optimization of a Positron Annihilation Lifetime Spectrometer to Measure Nanoscale Defects in Solids and Borane Cage Molecules in Aqueous Nitrate Solutions by : Matthew A. Ross
Download or read book Development and Optimization of a Positron Annihilation Lifetime Spectrometer to Measure Nanoscale Defects in Solids and Borane Cage Molecules in Aqueous Nitrate Solutions written by Matthew A. Ross and published by . This book was released on 2008 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Construction and Testing of a Positron Annihilation Lifetime Spectrometer by : Brian M. Wieland
Download or read book Construction and Testing of a Positron Annihilation Lifetime Spectrometer written by Brian M. Wieland and published by . This book was released on 2012 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron Annihilation Lifetime Spectroscopy (PALS) is a nuclear technique that was developed in the 1970s as a method to assess defects in materials. This technique has tremendous potential as a powerful tool for non-destructive quantification of the types and densities of defects within solids. Following the injection of positrons into a solid material, the positrons pair-annihilate at a rate dependent upon the density of electrons near the injection site. If there are lattice vacancies or dislocation defects near the injection site, the positrons are attracted to these areas, which have lower electron densities and thus give rise to longer positron lifetimes. Typical positron lifetimes in defect-free conductor-type metals are -'-'1OO ps, while lifetimes within defect regions are 2OO ps. In order to discern between these minute lifetime differences, a spectrometer with very good timing resolution has been constructed and optimized. The capabilities of the spectrometer have been tested using a 22Na positron emitter by performing source-based measurements of positron lifetimes in high-purity samples of aluminum, nickel, copper, and lead. Test results are in excellent agreement with currently accepted literature values, thus validating the apparatus and data analysis technique. This study is an important first step towards the development of a modern positron annihilation lifetime spectrometer for use in accelerator-based, gamma-induced positron annihilation spectroscopy (AG-PAS).
Book Synopsis Design and Performance Analysis of an Ultra-fast Digital Positron Annihilation Lifetime Spectrometer at The Ohio State University by : James Patrick Ralston
Download or read book Design and Performance Analysis of an Ultra-fast Digital Positron Annihilation Lifetime Spectrometer at The Ohio State University written by James Patrick Ralston and published by . This book was released on 2013 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Positron Annihilation Lifetime Spectroscopy (PALS) is a highly effective technique to quantify the lattice deformation in solid materials. The technique is based on amount of time it takes a free neutron to annihilate in the sample material. Since the timescales of positron lifetime are on the order of a nanosecond, high precision timing measurements are required to obtain useful measurements. Recent innovations in digital data acquisition technology has allowed digital systems to approach and surpass the timing capabilities of their analog counterparts. Digital acquisition systems also have the advantage of a generally simpler setup that offers equal capabilities at a lower cost. The digital system can potentially offer double the counting rates, as each detector in the system can measure both starting and stopping events. The spectrometer designed allows for high performance timing measurements, equal and better than analog and more expensive digital systems. Custom software, developed in C++/C, has been written for the data analysis and data acquisition and allows for very high counting rates. The system hardware was assembled with an ORTEC 905-21 fast plastic scintillation detector and a CAEN N6751 2 GS/s digitizer, the timing performance of the specific hardware combination used has been previously undetermined. The timing performance analysis was conducted with using a Co-60 button sized radiation source to measure coincident gamma rays. Since the gamma rays are emitted from the source at almost the exact same moment, the measured time difference between detected events can be used to measure the uncertainty in the timing of the spectrometer. The timing resolution of the spectrometer is characterized by the Full Width at Half Maximum (FWHM) of the measured Co-60 spectra. The measured value of the FWHM of the spectrometer was 208.5 ± 1.1 ps.
Book Synopsis Positron Spectroscopy of Solids by : Alfredo Dupasquier
Download or read book Positron Spectroscopy of Solids written by Alfredo Dupasquier and published by IOS Press. This book was released on 1995 with total page 830 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.
Book Synopsis Design and Implementation of a Digital Positron Annihilation Lifetime Spectrometer for Measurements in Graphite by :
Download or read book Design and Implementation of a Digital Positron Annihilation Lifetime Spectrometer for Measurements in Graphite written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A digital Positron Annihilation Lifetime Spectrometer was designed and used to perform measurements on three graphite materials, reactor grade graphite, pyrolytic graphite, and a foam graphite developed by Oak Ridge National Laboratory. Positrons are a useful probe of the microstructural features of matter since they are attracted to open-volume pores and defects where the electron density is lower than in other parts of the material. Various types of graphite were studied because of their importance in nuclear technology, including as a moderator in nuclear reactor cores. A lifetime spectrometer consists of a scintillation detector, photomultiplier tube, and equipment to perform timing analysis on the detected radiation. This equipment can either consist of analog pulse shaping and timing electronics or a system that digitizes and processes the radiation pulses. A new type of scintillation material, Lanthanum Bromide [LaBr3(Ce)], was tested and compared to the scintillator usually used for lifetime experiments, Barium Fluoride. The Lanthanum Bromide was expected to perform somewhat better than BaF2 based on its scintillation properties, and this was confirmed. The digital system was tested and its performance optimized. The digital lifetime spectrometer shared some similar equipment with a standard analog spectrometer and as such, both could be used simultaneously to take measurements. The digital spectrometer showed improvement in its timing resolution over the analog system. The measurements on graphite were more conclusive for the digital system than for the analog system, as results from the former matched published data well and were more consistent in general. This was due to the greater flexibility in timing methods and opportunity for optimization afforded by the digital system. Measurements on the graphites supported other work in the literature showing a lifetime of approximately 200 ps in the reactor grade and pyrolytic graphites with a second lifetime o.
Book Synopsis Positron Annihilation Lifetime Spectroscopy by : Yang Yu
Download or read book Positron Annihilation Lifetime Spectroscopy written by Yang Yu and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron annihilation lifetime spectroscopy (PALS); Free volume; Polymers; Amorphous; Crystalline; Semicrystalline; Ionic liquids
Book Synopsis Positron Beam Lifetime Spectroscopy at Lawrence Livermore National Laboratory by :
Download or read book Positron Beam Lifetime Spectroscopy at Lawrence Livermore National Laboratory written by and published by . This book was released on 1996 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Defect analysis is needed for samples ranging in thickness from thin films to large engineering parts. We are meeting that need with two positron beam lifetime spectrometers: on on a 3 MeV electrostatic accelerator and the second on our high current linac beam. The high energy beam spectrometer performs positron lifetime analysis on thick samples which can be encapsulated for containment or for in situ measurements in controlled environments. At our high current beam, we are developing a low energy, microscopically focused, pulsed positron beam to enable positron annihilation lifetime spectroscopy for defect specific, 3-D maps with sub-micron location resolution. The data from these instruments with the aid of first principles calculations of defect specific positron lifetimes.
Book Synopsis A New Beamline for Positron Annihilation Lifetime Spectroscopy by : Ryan Winslow Weed
Download or read book A New Beamline for Positron Annihilation Lifetime Spectroscopy written by Ryan Winslow Weed and published by . This book was released on 2011 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major aspect of this research is the development of a variable-energy PALS beamline based on a Surko-type buffer gas positron trap, the first of its kind in the world. A significant amount of work has gone into optimization of the timing and intensity characteristics of positron pulse. Successful implantation of 'Mills ideal function' bunching method has led to positron pulses of 800ps, allowing depth selective studies across a range of defect sizes, from point defects with lifetimes as low as 200ps, to large voids (~10 nm) resulting in lifetimes >50 ns. In addition to experimental development aspects, the materials investigations presented here focus on defects in semiconductor materials produced by ion implantation and focused laser pulses.
Book Synopsis Positron Annihilation Spectroscopy for Chemical Analysis (PASCA) by : Krishnan Venkateswaran
Download or read book Positron Annihilation Spectroscopy for Chemical Analysis (PASCA) written by Krishnan Venkateswaran and published by . This book was released on 1985 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Annihilation Studies of Solids and Surfaces by : Paul Richard Guagliardo
Download or read book Positron Annihilation Studies of Solids and Surfaces written by Paul Richard Guagliardo and published by . This book was released on 2011 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] This thesis describes the first positron annihilation studies undertaken in the Atomic, Molecular and Surface Physics group in the School of Physics at the University of Western Australia (UWA). We have studied a range of systems with differing positron annihilation characteristics with the aim of characterising their defect properties, and in the process have gained insight into the interactions of positrons and positronium with materials. The project started with establishing a positron annihilation laboratory. This entailed developing procedures to produce and safely handle sealed 22Na sources, and testing positron annihilation instrumentation and experimental methods. The project evolved through collaboration with physicists, engineers, chemists, materials scientists, metallurgists and medical scientists and through a number of interesting experimental explorations of the physical phenomena affecting positron annihilation. An overview of these investigations and a thesis synopsis is given below. Chapter 1 is an introduction to positron annihilation techniques, concentrating on the interactions of positrons (and positronium) with materials, and on the spectroscopies that exploit the annihilation processes for the purpose of studying condensed matter systems. Chapter 2 describes the testing and optimisation of the positron annihilation lifetime spectrometer and Doppler broadening spectrometer. In Chapter 3, positron annihilation has been applied to study cation vacancies in oxides that exhibit ionic bonding. Such vacancies have a relative negative charge and so attract positrons, and the relatively low electron density at these sites causes enhanced positron lifetimes. Oxides considered in this work are (a) rutile, (Ti,Nb)O2, sintered in air and Ar; (b) tin oxide, (Sn,Nb)O2 sintered in air; (c) monoclinic zirconia, (Zr,Nb)O2; (d) pollucite, Cs(1-x)Al(1-x)Si(2+x)O6 and (e) Ta- and Ti-doped Zn2TiO4. All systems except (c) showed enhanced lifetimes when doping or off-stoichiometry was increased. In Chapter 4, positron annihilation has been used to study the nanoporosity of cementitious materials. The mechanical properties of these materials are heavily influenced by porosity, with the volume and size distribution of pores controlling both the strength and durability of the material...
Book Synopsis Fluorescent Nanodiamonds by : Huan-Cheng Chang
Download or read book Fluorescent Nanodiamonds written by Huan-Cheng Chang and published by John Wiley & Sons. This book was released on 2018-11-12 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most comprehensive reference on fluorescent nanodiamond physical and chemical properties and contemporary applications Fluorescent nanodiamonds (FNDs) have drawn a great deal of attention over the past several years, and their applications and development potential are proving to be manifold and vast. The first and only book of its kind, Fluorescent Nanodiamonds is a comprehensive guide to the basic science and technical information needed to fully understand the fundamentals of FNDs and their potential applications across an array of domains. In demonstrating the importance of FNDs in biological applications, the authors bring together all relevant chemistry, physics, materials science and biology. Nanodiamonds are produced by powerful cataclysmic events such as explosions, volcanic eruptions and meteorite impacts. They also can be created in the lab by high-pressure high-temperature treatment of graphite or detonating an explosive in a reactor vessel. A single imperfection can give a nanodiamond a specific, isolated color center which allows it to function as a single, trapped atom. Much smaller than the thickness of a human hair, a nanodiamond can have a huge surface area that allows it to bond with a variety of other materials. Because of their non-toxicity, nanodiamonds may be useful in biomedical applications, such as drug delivery and gene therapy. The most comprehensive reference on a topic of rapidly increasing interest among academic and industrial researchers across an array of fields Includes numerous case studies and practical examples from many areas of research and industrial applications, as well as fascinating and instructive historical perspectives Each chapter addresses, in-depth, a single integral topic including the fundamental properties, synthesis, mechanisms and functionalisation of FNDs The first book published by the key patent holder with his research group in the field of FNDs Fluorescent Nanodiamonds is an important working resource for a broad range of scientists and engineers in industry and academia. It will also be a welcome reference for instructors in chemistry, physics, materials science, biology and related fields.
Book Synopsis Plastic Packaging by : Otto G. Piringer
Download or read book Plastic Packaging written by Otto G. Piringer and published by John Wiley & Sons. This book was released on 2008-06-25 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plastics are the most important class of packaging materials. This successful handbook, now in its second edition, covers all important aspects of plastic packaging and the interdisciplinary knowledge needed by food chemists, pharmaceutical chemists, food technologists, materials scientists, process engineers, and product developers alike. This is an indispensable resource in the search for the optimal plastic packaging. Materials characteristics, additives and their effects, mass transport phenomena, quality assurance, and recent regulatory requirements from FDA and European Commission are covered in detail with ample data.
Book Synopsis Anion Coordination Chemistry by : Kristin Bowman-James
Download or read book Anion Coordination Chemistry written by Kristin Bowman-James and published by John Wiley & Sons. This book was released on 2012-03-27 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building on the pioneering work in supramolecular chemistry from the last 20 years or so, this monograph addresses new and recent approaches to anion coordination chemistry. Synthesis of receptors, biological receptors and metallareceptors, the energetics of anion binding, molecular structures of anion complexes, sensing devices are presented and computational studies addressed to aid with the understanding of the different driving forces responsible for anion complexation. The reader is promised an actual picture of the state of the art for this exciting and constantly evolving field of supramolecular anion coordination chemistry. The topics range from ion channels to selective sensors, making it attractive to all researchers and PhD students with an interest in supramolecular chemistry.
Download or read book Graphdiyne written by Yuliang Li and published by John Wiley & Sons. This book was released on 2022-01-10 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Graphdiyne Discover the most cutting-edge developments in the study of graphdiyne from a pioneer of the field In Graphdiyne: Fundamentals and Applications in Renewable Energy and Electronics, accomplished chemist Dr. Yuliang Li delivers a practical and insightful compilation of theoretical and experimental developments in the study of graphdiyne. Of interest to both academics and industrial researchers in the fields of nanoscience, organic chemistry, carbon science, and renewable energies, the book systematically summarizes recent research into the exciting new material. Discover information about the properties of graphdiyne through theoretical simulations and experimental characterizations, as well as the development of graphdiyne with appropriate preparation technology. Learn to create new graphdiyne-based materials and better understand its intrinsic properties. Find out about synthetic methodologies, the controlled growth of aggregated state structures, and structural characterization. In addition to demonstrating the interdisciplinary potential and relevance of graphdiyne, the book also offers readers: A thorough introduction to basic structure and band gap engineering, including molecular and electronic structure, mechanical properties, and the layers structure of bulk graphdiyne Explorations of Graphdiyne synthesis and characterization, including films, nanotube arrays and nanowires, nanowalls, and nanosheets, as well as characterization methods Discussions of the functionalization of graphdiyne, including heteroatom doping, metal decoration, and absorption of guest molecules Rigorous treatments of Graphdiyne-based materials in catalytic applications, including photo- and electrocatalysts Perfect for organic chemists, electronics engineers, materials scientists, and physicists, Graphdiyne: Fundamentals and Applications in Renewable Energy and Electronics will also find its place on the bookshelves of surface and solid-state chemists, electrochemists, and catalytic chemists seeking a one-stop reference on this rising-star carbon material.
Book Synopsis Handbook of Fluoropolymer Science and Technology by : Dennis W. Smith
Download or read book Handbook of Fluoropolymer Science and Technology written by Dennis W. Smith and published by John Wiley & Sons. This book was released on 2014-05-05 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Fluoropolymer Science and Technology A comprehensive handbook on fluoropolymer synthesis, characterization, and processing Fluoropolymers, one of the more durable classes of polymer materials, are known to enable novel technologies as a result of their remarkable properties. As key components in industry applications, fluoropolymers have established commercial interest and scientists have discovered more efficient approaches of handling them. This book reviews up-to-date fluoropolymer platforms as well as recently discovered methods for the preparation of fluorinated materials. It focuses on synthesis, characterization, and processing aspects, providing guidelines for practicing scientists and engineers. In addition, the book covers: Concepts and studies from leading international laboratories, including academia, government, and industrial institutions Emerging technologies and applications in energy, optics, space exploration, fuel cells, microelectronics, gas separation membranes, biomedical instrumentation, and more Current environmental concerns associated with fluoropolymers, relevant regulations, and growth opportunities Overall, the chapters provide coverage of chemical methods and help the reader further understand how fluoropolymer research provides solutions for material challenges. The concepts in this book also inspire professionals to identify new markets and funding sources for fluoropolymer research and development.
Book Synopsis Membrane Technology and Applications by : Richard W. Baker
Download or read book Membrane Technology and Applications written by Richard W. Baker and published by John Wiley & Sons. This book was released on 2004-05-31 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: Table of Contents Preface Acknowledgments for the first edition Acknowledgments for the second edition 1 Overview of Membrane Science and Technology 1 2 Membrane Transport Theory 15 3 Membranes and Modules 89 4 Concentration Polarization 161 5 Reverse Osmosis 191 6 Ultrafiltration 237 7 Microfiltration 275 8 Gas Separation 301 9 Pervaporation 355 10 Ion Exchange Membrane Processes - Electrodialysis 393 11 Carrier Facilitated Transport 425 12 Medical Applications of Membranes 465 13 Other Membrane Processes 491 Appendix 523 Index 535.
Book Synopsis Dimensional Psychopathology by : Massimo Biondi
Download or read book Dimensional Psychopathology written by Massimo Biondi and published by Springer. This book was released on 2018-05-30 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an innovative approach to clinical assessment in psychiatry based on a number of psychopathological dimensions with a presumed underlying pathophysiology, that are related to fundamental phenomenological aspects and lie on a continuum from normality to pathology. It is described how the evaluation of these dimensions with a specific, validated rapid assessment instrument could easily integrate and enrich the classical diagnostic DSM-5 or ICD-10 assessment. The supplemental use of this dimensional approach can better capture the complexity underlying current categories of mental illness. The findings from a large patient sample suggest how this assessment could give a first glance at how variable and multifaceted the psychopathological components within a single diagnostic category can be, and thereby optimise diagnosis and treatment choices. Being short and easy to complete, this dimensional assessment can be done in a busy clinical setting, during an ordinary psychiatric visit, and in an acute clinical context, with limited effort by a minimally trained clinician. Therefore, it provides interesting and useful information without additional costs, and allows research work to be performed even in difficult settings.
