Status of the pulsed low energy positron beam system (PLEPS) at the Munich Research Reactor FRM-II

Sperr, P.; Egger, Werner; Kögel, G.; Dollinger, G.; Hugenschmidt, C.; Repper, R.; Piochacz, C.

doi:10.1016/j.apsusc.2008.05.307

Cited by 93 publications

(69 citation statements)

References 11 publications

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“…30,31 The positron beam energy was varied between 1 to 18 keV, and each lifetime spectra contained >5 × 10 6 counts accumulated with a count rate of ∼6 × 10 3 s −1 . The instrument timing resolution function was normally described by three dominant, energydependent, terms; these showed a mean width, averaged over all energies, of 299 (20) ps.…”

Section: Methodsmentioning

confidence: 99%

Nonstoichiometry accommodation in SrTiO3thin films studied by positron annihilation and electron microscopy

et al. 2013

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Accommodation of nonstoichiometry in SrTiO 3 pulsed laser deposited (PLD) films was investigated using positron annihilation lifetime spectroscopy and (scanning) transmission electron microscopy. Increasing PLD laser fluence changed the stoichiometry from Ti to Sr deficient. Cation vacancy defects were detected, and the concentration ratio of Sr to Ti vacancies, [V Sr ]/[V Ti ], was observed to increase systematically in the Sr-deficient region, although no change in the electron microscopy lattice images was detected. Increasing Ti deficiency resulted in the accommodation of SrO layers in planar defects, and in the formation of vacancy cluster defects. A change from V Ti to V Sr defect positron trapping was also detected.

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Section: Methodsmentioning

confidence: 99%

Nonstoichiometry accommodation in SrTiO3thin films studied by positron annihilation and electron microscopy

et al. 2013

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“…Depth-profiled PALS measurements on thin TO-CNF, as a function of energy (1-12 keV) and temperature (290-330 K), were carried out with pulsed low energy positron system (PLEPS) apparatus [9] at the high intensity positron source NEPOMUC (NEutron induced POsitron source MUniCh), by acquiring spectra containing 4×10…”

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

Modification of Free Volume due to Rigidness of Polymeric Matrix and Effects on Gas Transport Properties

Checchetto

Brusa

2017

Acta Phys. Pol. A

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Gas barrier properties of polymeric membranes with different rigidness of their matrix where studied by gas phase permeation measurements. Gas transport results in membranes made of epoxy resin with different cross linking densities and epoxy resin with dispersed few layer graphene fillers were discussed and compared in the framework of the free volume theory of diffusion. Transport in cellulose membranes was found to occur in the diffusion configurational regime. The physical description of the transport properties was based on positron annihilation lifetime spectroscopy measurements which allowed to evaluate experimentally the fractional free volume in epoxy resin membranes and the size of rigid elongated cavities in cellulose thin films.

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“…Las medidas de tiempo de vida que se presentan en este trabajo fueron efectuadas en el espectrómetro PLEPS (Pulsed Low Energy Positron Beam) [15] situado en la facility europea NEPOMUC (Neutron induced POsitron source MUniCh) [16]. Las medidas fueron llevadas a cabo variando la energía de implantación de los positrones entre 0.5-18keV.…”

Section: C) Espectroscopía Temporal De Aniquilación De Positrones (Pals)unclassified

Caracterización de nanoestructuras sub-superficiales utilizando espectroscopía de aniquilación de positrones

Macchi

2013

Matéria (Rio J.)

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RESUMENLa espectroscopía de aniquilación de positrones (PAS) ha demostrado ser una poderosa herramienta para el estudio de defectos en sólidos ya que posee características únicas debido a su alta sensibilidad a la presencia de defectos tales como vacancias, aglomerados de vacancias o nanohuecos. Asimismo, PAS posibilita la identificación y caracterización de cada uno de estos defectos. Existen diferentes variantes experimentales de PAS tales como la espectrometría temporal positrónica, que permite identificar y cuantificar los distintos tipos de defectos, y el ensanchamiento Doppler que brinda información no solo sobre los defectos sino, también, sobre las especies atómicas que decoran los sitios de atrapamiento de los positrones. Estas técnicas, acopladas a un haz de positrones lentos permiten estudiar, además, defectos sub-superficiales en materiales con espesores inferiores al micrómetro, films y coatings. En este trabajo, se presentan dos ejemplos que ponen de manifiesto la potencialidad de PAS para el estudio de defectos sub-superficiales en: i) vidrios de sílice implantados con iones de oro y ii) oro rugosado. Palabras clave: Aniquilación de Positrones, Películas delgadas, implantación de iones, defectos subsuperficiales ABSTRACTPositron annihilation spectroscopy (PAS) has proved to be a powerful tool for the study of defects in solids due to its high sensitivity to the presence of defects such as vacancies, vacancy agglomerates or voids. Furthermore, PAS allows to identify and characterize each of these defects. There are different experimental variations of PAS technique such as positron annihilation lifetime spectroscopy (PALS), which allows to identify and quantify different types of defects and Doppler Broadening that provides information not only about the defects but also on the atomic species that decorate the positrons trapping sites (ie, chemical environments). These experimental techniques coupled with a slow positron beam can be used to study defects profile and subsurface defects in films and coatings. In this paper, we present two examples that demonstrate the potential of PAS for the study of subsurface defects in: i) silica glass implanted with gold ions and ii) high-area nanostructured gold films..

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Status of the pulsed low energy positron beam system (PLEPS) at the Munich Research Reactor FRM-II

Cited by 93 publications

References 11 publications

Nonstoichiometry accommodation in SrTiO3thin films studied by positron annihilation and electron microscopy

Nonstoichiometry accommodation in SrTiO3thin films studied by positron annihilation and electron microscopy

Modification of Free Volume due to Rigidness of Polymeric Matrix and Effects on Gas Transport Properties

Caracterización de nanoestructuras sub-superficiales utilizando espectroscopía de aniquilación de positrones

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