Results 201 to 210 of about 1,787,488 (253)
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Macromolecules, 2018
In order to characterize the free volume of a homologous series all-aromatic poly(ether imide) (PEI) membranes, two positron annihilation techniques were utilized: positron annihilation lifetime spectroscopy (PALS) and Doppler broadening (DB) of ...
Z. Madzarevic +3 more
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In order to characterize the free volume of a homologous series all-aromatic poly(ether imide) (PEI) membranes, two positron annihilation techniques were utilized: positron annihilation lifetime spectroscopy (PALS) and Doppler broadening (DB) of ...
Z. Madzarevic +3 more
semanticscholar +1 more source
Antiplasticization of a polyamide: a positron annihilation lifetime spectroscopy study
Polymer, 2004Abstract In order to modify the transport properties of the amorphous polyamide Trogamid-T™, several additives with structural characteristics that produce antiplasticization have been tested. Positron annihilation lifetime spectroscopy (PALS) has been used to determine both the size of free volume holes and the number of holes (free fractional free ...
Agustin Etxeberría Lizárraga
exaly +2 more sources
Design of a slow pulsed positron beam for positron annihilation lifetime spectroscopy
2007 IEEE Nuclear Science Symposium Conference Record, 2007Positron annihilation spectroscopy provides a useful tool for the non-destructive study of subsurface microscopic defects. Variations in the electronic environment, from that of the bulk of the material, caused by defects introduce Coulombic forces which cause positrons to localize at the site of defects. This lifetime can vary from nanoseconds, if the
Alfred G. Hathaway +3 more
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Slow Positron Pulsing System for Variable Energy Positron Lifetime Spectroscopy
Japanese Journal of Applied Physics, 1991A positron pulsing system has been constructed for variable energy positron lifetime spectroscopy. The system consists of a reflection type chopper, a sub-harmonic prebuncher, and a double harmonic buncher. By operating the system with an intense slow positron beam generated by an electron linac, positron lifetime spectra have been successfully ...
Ryoichi Suzuki +6 more
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Open volume in bioadhesive detected by positron annihilation lifetime spectroscopy
Acta Biomaterialia, 2010Barnacles attach to a wide variety of surfaces underwater and show substrate-specific adhesion mechanisms. Investigating and understanding these mechanisms is a key for developing new technical adhesives. We expected open volume (porosity) at the sub-nanometre scale to occur in barnacle adhesive.
Klaus, Rätzke +6 more
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Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production
Defect and Diffusion Forum, 2012A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair ...
Wagner, A. +6 more
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Mechanical Stability of Porous Copolymers by Positron Annihilation Lifetime Spectroscopy
The Journal of Physical Chemistry C, 2015<p>A set of porous copolymer samples (VP-TRIM, VP-DVB, and VP-DMN) under mechanical stress up to 1.3 GPa was studied in situ using positron annihilation lifetime spectroscopy. A few stages of porosity evolution dissimilar in changes of the pore size distribution (PSD) were observed.
R. Zaleski +2 more
semanticscholar +3 more sources
Development of an Electron-Positron Source for Positron Annihilation Lifetime Spectroscopy
2007Abstract : The extremely strong fields produced by focusing powerful laser pulses into minute volumes of material enable relativistic effects to be used to generate radiation, to accelerate particles, and to produce electrons and positrons from vacuum.
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Positron lifetime spectroscopy of internally oxidised Ag-In alloys
Journal of Physics: Condensed Matter, 1989The effects of In2O3 precipitates on positron lifetimes after internal oxidation of alpha -Ag-In alloys have been investigated. A positron trap associated with the lifetime tau =205(3) ps was detected. On the basis of the experimental results obtained for different oxidation kinetics parameters, a trapping model is proposed according to which positrons
D Wegner, K P Lieb
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Nanovoids in Glasses and Polymers Probed by Positron Annihilation Lifetime Spectroscopy
2011Nanovoids in As2S3-based glasses (As 2S3, (As2S3)85Ag 15, and (As2S3)85(AgI) 15), a polymer and a As2S3-polymer nanocomposite were studied using the positron annihilation lifetime spectroscopy (PALS) technique. After computer treatment of the PALS data recorded, it was found that only two components τ 1 (short-lived) near 0.2 ns and τ 2 (long-lived ...
Kavetskyy T. +5 more
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