2 edition of Slow positron studies of surface and subsurface phenomena. found in the catalog.
Slow positron studies of surface and subsurface phenomena.
James Alexander Baker
Thesis (Ph.D.), University of East Anglia, School of Mathematics and Physics, 1989.
The slow-positron beam technique - a tool for the study of vacancy-type defects in semiconductors Diffusion and Defect Data Part B (Solid State Phenomena) () R. Krause-Rehberg, H. S. Leipner, T. Abgarjan, and A. Polity. Within the last decade powerful methods have been developed to study surfaces using bright low-energy positron beams. These novel analysis tools exploit the unique properties of positron interaction with surfaces, which comprise the absence of exchange interaction, repulsive crystal potential and positron trapping in delocalized surface states at low energies. By applying reflection high.
The free volume sizes and distributions and multilayer structures in asymmetric thin layer polyamide membranes in the wet state have been first time measured using the variable monoenergy slow positron beam (VMSPB). This paper presents a newly developed method which combines the technique of plasma-enhanced chemical vapor deposition to form a barrier layer for high-vacuum condition to seal . Design for a New Low Energy Positron Beam for Surface Studies, Alex Weiss, in Positron Annihilation (proceedings of the Seventh International Conference on Positron Annihilation, India), edited by P.C. Jain, R.M. Singru and K.P. Gopinathan, World Scientific Publ., Singapore, () pp. 5.
Experimental setup and the principle. Figure 1 shows a schematic diagram of the experimental setup. The transversely spin-polarized positron beam, which was generated by a 22 Na source ( MBq) and an electrostatic apparatus, was implanted into the center of the sample The diameter and the spin polarization (P +) of the positron beam were 1 mm and , respectively. Application of Positron Annihilation Induced Auger Electron Spectroscopy to the Study of Surface Chemistry, A.H. Weiss, G. Yang, J.H. Kim, A. Nangia, and N.G. Fazleev, Proceedings of the Fifth International Workshop on Positron and Positronium Chemistry (PPC5), Journal of Radioanalytical and Nuclear Chemistry, , ().
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Topics: 20K - Solid-state physics, 20B - Elementary particles, high energy physics, Slow positron studies of surface and subsurface phenomena [ Surface physics!]Author: J.A Baker.
Slow positron studies of surface and subsurface phenomena. Author: Baker, James Alexander. ISNI: Awarding Body: University of East Anglia Current Institution: University of East Anglia Date of Award: Availability of Full Text. The zone below the surface in pure Zr exposed to dry sliding is the subject of studies using positron lifetime methods.
New type of the defect depth profile is observed. The paper presents studies of the defect distribution, detected by the positron annihilation method in the subsurface zone (SZ) of copper samples after dry sliding wear. It takes advantage of a new experimental technique based on scanning of the positron implantation by: 9.
The surface degradation was also shown by the positron studies to be permanent, even after hydrophobic recovery, the silica-like degradation layers persists. By Slow positron studies of surface and subsurface phenomena. book the slow positron beam results of the block copolymer to that of it's constituent homopolymers, we were able to use the high resolution of this technique at the surface of.
The annealing behavior of the subsurface zone (SZ) in pure bismuth induced by dry sliding was studied using the positron lifetime measurement.
This measurement allows us to detect the SZ and its recovery, and recrystallization processes. The comparative measurements of the sample exposed to compression revealed the thermal stability of the SZ.
A new pulsed mono-energetic slow positron beam as well as the conventional positron annihilation lifetime spectroscopy (PALS) have been applied to study the sub-surface and the bulk of epoxy polymer. Significant changes of o-Ps parameters were found at a short distance from the surface.
The lifetime of o-Ps was observed to decrease with increasing the positron implantation depth, while its. Journal of Electron Spectroscopy and Related Phenomena, 19 () Elsevier Scientific Publishing Company, Amsterdam Printed in The Netherlands Short communication A GOLD MODERATOR SURFACE PREPARATION FOR INCREASED SLOW POSITRON YIELD* S PENDYALA Physics Department, State Uniuersity of New York, College at Fredonia, Fredonia, New York.
Roy's authoritative book Positron Studies of In the s Roy's interests broadened to include slow positron beams and their applications to surface and near-surface phenomena. He became a member of the positron consortium at Brookhaven National Laboratory, where the installation of two Anger cameras at either side of the intense positron.
Vehanen's 71 research works with 2, citations and reads, including: Vacancy-Type Defects in Ion-Implanted Si Studied By Slow Positron Beam. 22 OctoberVolume, Number Surface Analysis andAtoi Physics with Slow Positron Bea Allen P.
Miil Positrons were predicted bythe Dirac (1) theory ofthe electron and were dis- covered by Anderson (2) 50 years ago.
Being the antimatter equivalent ofelec- trons, positrons have precisely the same massandspin as electrons, butprecisely the opposite charge and magnetic mo- ment (3). We describe an apparatus for producing an intense low energy positron beam of well defined energy by moderating the decay positrons from a radioactive source using a clean single crystal convertor with high conversion efficiency (ε≃10 −3).These positrons are used as a probe to study well characterized surfaces in an ultra‐high vacuum system.
The magnetically focussed beam can deliver a. Metals and Alloys  A study on vacancy-tpe defects in the electroless Cu measured with a monoenergetic positron beam Kimihiro Yamanaka, Akira Uedono. Scripta Materia 8 ().  Recrystallization in subsurface zone seen by positron annihilation Jerzy Dryzek, Anna Kozłowska Tribology International, In Press, Corrected Proof, Available online 6 August The diffusion trapping model has been applied to slow positron annihilation in He+ irradiated polystyrene and polystyrene – polystyrene bilayers.
The S-parameter and the positron lifetime have been calculated as a function of the incident positron energy. The effect of the fluence upon the nature of the S-parameter curve has been discussed.
At the University of Bath the positron laboratory is equipped with two magnetic-transport positron beam systems for depth profiling the structural, chemical and electronic properties of materials from the surface to depths of a few micrometres, and a project beam system for the study of fundamental positron-atom collision phenomena.
Slow Positron Beam Apparatus for Surface and Subsurface Analysis of Samples in Air. Nagayasu Oshima, Brian E. O'Rourke, Ryunosuke Kuroda, Ryoichi Suzuki, Hiromichi Watanabe 1, Shoji Kubota 1, Kazuki Tenjinbayashi 1, Akira Uedono 1 and Noriyosu Hayashizaki 2.
Published 25 May • © The Japan Society of Applied Physics. Due to multiple phenomena contributing to positron diffusion in solid, the measured S-parameter from annihilation at the surface (S sur) and the S-parameter from annihilation events in the interior (S bulk) of the sample.
The solution of the Diffusion Trapping Model (DTM) for the 1D case allows us to obtain the following relationship for the. Recent advances in slow positron beam techniques are making it possible to study the interactions of low-energy positrons with gas molecules and solid surfaces and to measure the properties of free positronium atoms.
New surface related results include the observation of surfaces with negative positron affinity and the thermionic emission of slow positronium atoms, low-energy positron. After slow positron beam apparatus and techniques were developed, they were applied to the study of depth proﬁles and the varied properties of polymer structures from surface to bulk,35–41 Compared with well-established slow posi-tron beam methods for the depth proﬁling of defects in amorphous or crystalline solids,35,38–41 the study of.
Positron annihilation lifetime spectroscopy (PALS) is an experimental technique whereby the lifetime spectrum of positrons injected into a material is measured. Analysis of this spectrum can be used to characterize defects in the material.
While radioisotope positron sources are often used for PALS, there are several advantages of using mono-energetic, slow positron beams. A pulsed slow-positron beam, enabling positron lifetime studies in thin semiconductor layers and near-surface regions, is presented.
The positron beam is modulated with a radio-frequency beam bunching system into pulses below ps full-width at half-maximum at a repetition rate of 33 MHz.Slow Positron Beam Apparatus for Surface and Subsurface Analysis of Samples in Air.
Applied Physics Express4 (6), DOI: /APEX Wei-Chi Chao, Shu-Hsien Huang, Quanfu An, Der-Jang Liaw, Ying-Chi Huang, Kueir-Rarn Lee, Juin-Yih Lai.This review is concerned with the utilization of the positron-electron annihilation phenomenon in studies of the physics of condensed matter.
The theory of the annihilation process is outlined, the importance of the two-photon mode of decay is established, and it is described how the observable results depend on the initial positron and electron states of the system.