Topic
Positron annihilation spectroscopy
About: Positron annihilation spectroscopy is a research topic. Over the lifetime, 2170 publications have been published within this topic receiving 32840 citations. The topic is also known as: PAS & PALS.
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TL;DR: In this article, a review of advances in the study of solid surfaces and thin films using variable-energy positron beams is presented, with more emphasis on the most recent measurements and interpretations than on the chronology of various developments.
Abstract: Recent advances in the study of solid surfaces and thin films using variable-energy positron beams are reviewed. In the first part the authors discuss the process of positron moderation and technical aspects of positron beam production and application. The second part is (roughly) organized in sections that apply to increasing time scales appropriate to the positron-solid interaction. These are (a) first encounter and scattering effects, (b) energy loss and stopping profiles, (c) diffusion of thermalized positrons, (d) positron-surface interactions, and (e) studies of defects near surfaces and interfaces. The review is written with more emphasis on the most recent measurements and interpretations than on the chronology of various developments.
1,316 citations
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TL;DR: ZnO nanorod arrays were fabricated using a hydrothermal method and found that, while the defect emission can be significantly reduced by annealing at 200 degrees C, the rods still have large defect concentrations as confirmed by their low positron diffusion length and short PL decay time constants.
Abstract: ZnO nanorod arrays were fabricated using a hydrothermal method. The nanorods were studied by scanning electron microscopy, photoluminescence (PL), time-resolved PL, X-ray photoelectron spectroscopy, and positron annihilation spectroscopy before and after annealing in different environments and at different temperatures. Annealing atmosphere and temperature had significant effects on the PL spectrum, while in all cases the positron diffusion length and PL decay times were increased. We found that, while the defect emission can be significantly reduced by annealing at 200 °C, the rods still have large defect concentrations as confirmed by their low positron diffusion length and short PL decay time constants.
667 citations
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TL;DR: Positron annihilation spectroscopy for chemical analysis (PASCA) has been developed to analyze the microstructure of polymers as discussed by the authors, where the positronium atom is trapped in the atomic-scale holes which have a size ranging from 1 to 10 A. Theoretical aspects, experimental developments, and examples in analyzing the microstructures of epoxy, PEEK, and PMMA polymers are presented.
Abstract: Positron annihilation spectroscopy for chemical analysis (PASCA) has been developed to analyze the microstructure of polymers. Positron annihilation lifetime measurements give direct information about the dimension and contents of free-volume holes in amorphous materials. The angular correlation measurements of positron annihilation radiation give additional information about the shape of the free-volume holes in oriented polymeric materials. The unique capability of PASCA to probe free-volume properties is from the fact that positronium atom is trapped in the atomic-scale holes which have a size ranging from 1 to 10 A. Theoretical aspects, experimental developments of PASCA, and examples in analyzing the microstructures of epoxy, PEEK, and PMMA polymers are presented.
664 citations
Book•
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01 Oct 1988
TL;DR: Y.C. Jean and D.M. Schrader as mentioned in this paper proposed the slow Positron as a probe of surface chemistry. But their approach was limited to the detection of phase transition and other structural changes.
Abstract: Chapter 1. Introduction (D.M. Schrader and Y.C. Jean). 2. Theoretical Aspects of Positronic Systems (D.M. Schrader). 3. Experimental Techniques in Positron and Positronium Chemistry (Y.C. Jean and D.M. Schrader). 4. Radiation Chemistry: Intraspur Effects and Positronium Formation Mechanics (Y. Ito). 5. Positrons and Positronium in Liquids (H. Nakanishi and Y.C. Jean). 6. Positrons and Positronium Annihilation in Gases (S.C. Sharma). 7. The Slow Positron as a Probe of Surface Chemistry (Y.C. Jean). 8. Positrons and Positronium in Molecular Solids (S.J. Wang and Y.C. Jean). 9. Positron Annihilation Spectroscopy for Chemical Analysis (PASCA) (K.L. Cheng and Y.C. Jean). 10. Positronium Annihilation as a Probe for the Determination of Phase Transitions and other Structural Changes in Micellar Systems, Microemulsions, Surfactant Vesicles, and Polymers (H.J. Ache). 11. Biological Applications of Positron Annihilation (Y.Y. Wang and Y.C. Jean). Subject Index. Author Index.
453 citations