Results 191 to 200 of about 1,787,488 (253)

Positron lifetime spectroscopy in nanocrystalline iron

Physics Letters A, 1987
Abstract First positron annihilation measurements were performed on nanocrystalline iron specimens which are polycrystals with very small crystallite size (5–10 nm). The lifetimes τ 1 = 180 ± 15 ps, τ 2 = 360 ± 30 ps and long-lived components between 1 and 4 ns are attributed to vacancy-size free volumes in the crystallite interfaces, to ...
H.E. Schaefer, R. Würschum
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Preparation and positron lifetime spectroscopy of nanocrystalline metals

Nanostructured Materials, 1993
Abstract Nanocrystalline metals prepared by evaporation or sputtering with crytallite condensation and compaction were studied by means of positron lifetime spectroscopy in order to obtain information on structural free volumes in the crystallite interfaces.
R. Würschum, W. Greiner, H.-E. Schaefer
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Digital positron lifetime spectroscopy at EPOS

Applied Surface Science, 2008
Abstract As the digital equipment to measure positron lifetimes gets cheaper and more widely used, it is decided that EPOS, the ELBE positron source will sample the signals from the photomultipliers directly and evaluate it online or offline by digital means.
Krille, A., Krause-Rehberg, R., Jungmann, M., Becvar, F., Brauer, G.   +4 more
openaire   +2 more sources

Positron annihilation lifetime spectroscopy of annealed tungsten

Kerntechnik, 2022
Abstract Three samples of 99.97% pure rolled tungsten were annealed at 700 °C, 1000 °C, and 1400 °C in a vacuum of about 10−6 mbar for 1 h. Then the effects of annealing were investigated. For this purpose, defects and their structure in the three annealed samples and the as-received sample, were studied, characterized, and compared by ...
Mahnaz Torabi, Omidreza Kakuee, Samad Sobhanian, Mohammad Kouhi   +3 more
openaire   +1 more source

Comparative studies of methyl orange adsorption in various metal-organic frameworks by nitrogen adsorption and positron annihilation lifetime spectroscopy

, 2020
In this work, typical metal-organic frameworks (MOFs) MIL-101-Cr, MIL-53-Al and ZIF-8 with high specific surface areas were synthesized and applied in the removal of anionic dye methyl orange (MO) from water. Nitrogen adsorption and positron annihilation
Xiao-Wei Zhang, Libing Qian, Shiju Yang, Yu-hong Peng, Bang-Yun Xiong, Jing-Jing Li, P. Fang, Chunqing He   +7 more
semanticscholar   +1 more source

Positron lifetime spectroscopy in ordered nanoporous polymers

Journal of Polymer Science Part B: Polymer Physics, 2013
ABSTRACTPositron annihilation lifetime spectroscopy (PALS) is a common technique used to characterize the porosity of polymers. Here, we expand its use to the study of ordered nanoporous polymer monoliths. Polystyrene (PS) monoliths with aligned cylindrical pores ranging in diameters from 15 to 35 nm were examined.
Jason Engbrecht, David Green, Marc A. Hillmyer, David Olson, Eric M. Todd   +4 more
openaire   +1 more source

Source correction in positron annihilation lifetime spectroscopy

Journal of Physics: Condensed Matter, 1996
The positron lifetimes in a source have been measured. The fraction of positrons annihilated in salt and in the Kapton supporting foils has been determined as a function of the atomic number Z of the sample. All of the experimental results have been compared with calculated values obtained from a computer program based on a Monte Carlo algorithm.
N Djourelov, M Misheva
openaire   +1 more source

A supervised machine learning approach using naive Gaussian Bayes classification for shape-sensitive detector pulse discrimination in positron annihilation lifetime spectroscopy (PALS)

Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment, 2019
The acquisition of high-quality and non-artefact afflicted positron lifetime spectra is crucial for a profound analysis, i.e. the correct lifetime spectra decomposition for retrieving the true information.
D. Petschke, T. Staab
semanticscholar   +1 more source

Single shot positron annihilation lifetime spectroscopy

Applied Physics Letters, 2006
Recent developments in positron trapping technology have made possible experimentation with dense interacting positronium gases. Along with these capabilities comes a need for suitable measurement techniques, and accordingly we have developed a method to measure positronium lifetimes from a single intense burst of positrons.
D. B. Cassidy, S. H. M. Deng, H. K. M. Tanaka, A. P. Mills   +3 more
openaire   +1 more source

Positron Annihilation Lifetime Spectroscopy in the analysis of microstructural changes of Y-TZP ceramics

International Journal of Materials and Product Technology, 2009
Positron Annihilation Lifetime Spectroscopy (PALS) technique was used for microstructural characterisation of Y-TZP ceramics. Spectroscopic measurements were carried out on ceramic surfaces subjected to tribological tests.
Esposito L., Parente P., TIMELLINI, GIORGIO, Tucci A., Ferro G.   +4 more
exaly   +2 more sources