On the application of methods of positron annihilation spectroscopy for studying radiation-stimulated processes in chalcogenide glassy semiconductors

Unirradiated and γ-irradiated (average energy E = 1.25 MeV and dose Φ = 2.41 MGy) chalcogenide glassy semiconductors (CGSs) As2S3 and Ge15.8As21S63.2 are studied by positron annihilation lifetime spectroscopy (PALS) and Doppler broadening of the 0.511-MeV annihilation line (DBAL). Two 22Na positron sources with activities of 0.6 and 2.0 MBq and Kapton film thicknesses of 8.0 and 25.0 μm, respectively, are used. It is shown that radiation-induced changes in the PALS parameters of the CGS types under study are within measurement errors. The DBAL method appeared more efficient and accurate for studying radiation-stimulated processes in CGSs. © 2014 Pleiades Publishing, Ltd

Structural modification of chalcogenide glasses by gamma-irradiation studied with DBAL technique

The original experimental results on the study of structural modification of chalcogenide glasses by 60Co γ-irradiation with energy of 1.25 MeV and dose of 2.41 MGy for As2S3, Ge15.8As21S63.2, Ge9.5As28.6S61.9 and Ge23.5As11.8S64.7alloys using Doppler broadening of annihilation line (DBAL) technique are reported. The γ-irradiation-induced effect is analyzed in terms of Doppler S and W annihilation parameters. In particular, the observed different slope of S -W plots for glassy (g-) As2S3 and g-Ge15.8As21S63.2studied in the unirradiated and γ-irradiated states indicates that the defect structure of these alloys in the radiation-modified state is different, obviously, as a result of various mechanisms of radiation-induced defect formation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Carbonization in boron-ion-implanted polymethylmethacrylate as revealed from Raman spectroscopy and electrical measurements

© 2016 Taylor and Francis Group, LLC. The results of Raman spectroscopy and electrical measurements of 40 keV boron-ion-implanted polymethylmethacrylate with ion doses from 6.25 × 1014 to 5.0 × 1016 ions/cm2 are reported for the first time. The Raman spectra recorded in the 400-3800 cm-1 range, showing the formation of new carbon-carbon bands for the as-implanted samples at higher ion doses (>1016 ions/cm2), are found to be an additional support for carbonization processes earlier revealed by slow positrons. The current-voltage dependences at 360 K testify also that the as-implanted samples examined with higher fluences (3.75 × 1016 and 5.0 × 1016 ions/cm2) have created a very thin conductive layer or conductive joints due to carbonization

Positron annihilation study of the juniperus communis based biomaterial NEFROVIL

© Springer Science+Business Media Dordrecht 2015. The results of positron annihilation lifetime (PAL) measurements of the Juniperus communis based biomaterial NEFROVIL are reported for the first time. Three- and four-component fittings were applied to deconvolute the PAL spectrum. In order to determine which fitting procedure is most suited, a maximum entropy lifetime (MELT) analysis was also performed. It was found that the nanovoid topology of this biomaterial is constructed by small and large free-volume holes identified by the ortho-positronium lifetime parameters in the most suitable fourcomponent fitting procedure

Doppler broadening of the annihilation line study of organic-inorganic hybrid ureasil-based composites

© Springer Science+Business Media Dordrecht 2015. The organic-inorganic hybrid ureasil-based composites, containing polyether chains covalently linked to a silica framework through urea bridges, referred as ureasilicates or ureasils, and semiconducting As2S3clusters, are investigated using Doppler broadening of annihilation line technique. It is established that the Doppler S and W parameters show significant structural difference between the pure ureasil and the As2S3-ureasil composites, the effect is more essential as the loading fraction of As2S3increases. The new Doppler broadening results obtained in this work are found to be in consistent with the earlier reported results of positron annihilation lifetime measurements of the same materials

Low-temperature positron annihilation study of B⁺-ion implanted PMMA

Temperature dependent positron annihilation lifetime spectroscopy (PALS) measurements in the range of 50–300 K are carried out to study positronium formation in 40 keV B+-ion implanted polymethylmethacrylate (B:PMMA) with two ion doses of 3.13·10¹⁵ and 3.75·10¹⁶ ions/cm². The investigated samples show the various temperature trends of ortho-positronium (o-Ps) lifetime τ3 and intensity I3 in PMMA before and after ion implantation. Two transitions in the vicinity of ∼150 and ∼250 K, ascribed to γ and β transitions, respectively, are observed in the PMMA and B:PMMA samples in consistent with reference data for pristine sample. The obtained results are compared with room temperature PALS study of PMMA with different molecular weight (Mw) which known from literature. It is found that B⁺-ion implantation leads to decreasing Mw in PMMA at lower ion dose. At higher ion dose the local destruction of polymeric structure follows to broadening of lifetime distribution (hole size distribution)

High-dose boron and silver ion implantation into PMMA probed by slow positrons: Effects of carbonization and formation of metal nanoparticles

© Published under licence by IOP Publishing Ltd.The Doppler broadening slow positron beam spectroscopy (SPBS) data for the previously observed effect of carbonization in high-dose (>1016 ion/cm2) 40 keV boron-ion-implanted polymethylmethacrylate (B:PMMA) and another one obtained for the effect of formation of metal nanoparticles in high-dose 30 keV silver-ion-implanted polymer (Ag:PMMA) are compared. Following to the Doppler broadening SPBS results, a difference in the high-dose ion-irradiation-induced processes in B:PMMA and Ag:PMMA is detected

Low-temperature positron annihilation study of B⁺-ion implanted PMMA

© 2014 AIP Publishing LLC. Temperature dependent positron annihilation lifetime spectroscopy (PALS) measurements in the range of 50-300K are carried out to study positronium formation in 40 KeV B+-ion implanted polymethylmethacrylate (B:PMMA) with two ion doses of 3.13 × 1015 and 3.75 × 1016 ions/cm2. The investigated samples show the various temperature trends of ortho-positronium (o-Ps) lifetime τ3 and intensity I3 in PMMA before and after ion implantation. Two transitions in the vicinity of ~150 and ~250 K, ascribed to γ and β transitions, respectively, are observed in the PMMA and B:PMMA samples in consistent with reference data for pristine sample. The obtained results are compared with room temperature PALS study of PMMA with different molecular weight (Mw) which known from literature. It is found that B+-ion implantation leads to decreasing Mw in PMMA at lower ion dose. At higher ion dose the local destruction of polymeric structure follows to broadening of lifetime distribution (hole size distribution)

On the application of methods of positron annihilation spectroscopy for studying radiation-stimulated processes in chalcogenide glassy semiconductors

Unirradiated and γ-irradiated (average energy E = 1.25 MeV and dose Φ = 2.41 MGy) chalcogenide glassy semiconductors (CGSs) As2S3 and Ge15.8As21S63.2 are studied by positron annihilation lifetime spectroscopy (PALS) and Doppler broadening of the 0.511-MeV annihilation line (DBAL). Two 22Na positron sources with activities of 0.6 and 2.0 MBq and Kapton film thicknesses of 8.0 and 25.0 μm, respectively, are used. It is shown that radiation-induced changes in the PALS parameters of the CGS types under study are within measurement errors. The DBAL method appeared more efficient and accurate for studying radiation-stimulated processes in CGSs. © 2014 Pleiades Publishing, Ltd