| 1. |
- Kantre, Karim-Alexandros, et al.
(författare)
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Assessing electronic energy loss of heavy ions detected in reflection geometry
- 2021
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Ingår i: Surface and Interface Analysis. - : John Wiley & Sons. - 0142-2421 .- 1096-9918. ; 53:7, s. 650-657
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Tidskriftsartikel (refereegranskat)abstract
- We study energy loss spectra of bromine ions scattered from silver thin films in the range of 4 to 36 MeV in forward reflection geometry. The different contributions to the energy loss were analyzed by complementary Monte-Carlo simulations. We assess the dependence of the scattering yield as well as nuclear and electronic losses on the penetration depth of detected ions. To investigate the entanglement of energy loss and depth information, electronic stopping cross sections were deduced from the experimental spectra by two different approaches: a) assuming a single scattering model and b) making use of Monte-Carlo simulations. The data obtained from the two approaches are compared and we assess the relative contributions from nuclear stopping as well as from the effect of multiple scattering on trajectory length. Results of both methods are compared to data from literature, to SRIM predictions and discussed in the context of composition depth‑profiling.
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| 2. |
- Kantre, Karim-Alexandros, et al.
(författare)
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Combination of in-situ ion beam analysis and thermal desorption spectroscopy for studying deuterium implanted in tungsten
- 2021
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Ingår i: Physica Scripta. - : Institute of Physics Publishing (IOPP). - 0031-8949 .- 1402-4896. ; 96:12
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a combinatorial approach integrating ion implantation followed by thermal annealing and simultaneous in situ ion beam analysis with thermal desorption spectroscopy in a single set-up. Atomic and molecular deuterium ions of 3 keV were implanted into bulk tungsten with doses exceeding 1 x 10(22) ions m(-2). Depth profiling of both, protium and deuterium was performed by elastic recoil detection analysis, while simultaneously the outgassing rates of molecular deuterium by thermal desorption spectroscopy were monitored during temperature ramps from room temperature to approximate to 1400 K. The combination of the two techniques in situ is shown capable to identify the distinct retention behavior of deuterium at different temperatures and in different reservoirs, e.g. located close to the surface and diffused deep into the material. Ex-situ scanning electron microscopy confirmed blister formation, and recovery of the initial surface morphology after high temperature annealing, in analogy to comprehensive ex-situ studies.
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| 3. |
- Kantre, Karim-Alexandros, et al.
(författare)
-
Combined in-situ ion beam analysis and thermal desorption spectroscopy for studying deuterium retention in tungsten
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We demonstrate a combinatory approach integrating ion implantation followed by thermal annealing and simultaneous in‑situ ion beam analysis with thermal desorption spectroscopy to be used for investigating the retention of deuterium in tungsten. All sample preparation, modification and analysis steps are performed in a single system. Atomic and molecular deuterium ions of 3 keV were implanted into tungsten bulk samples with highest doses significantly exceeding 1x1022 ions/m2. We demonstrate depth profiling of different hydrogen species by elastic recoil detection analysis, while the outgassing rate of molecular deuterium was simultaneously monitored by thermal desorption spectroscopy in different annealing processes (continuous and stepwise temperature ramping) from room temperature up to ≈1400 K. No pronounced narrow peaks were detected in the thermal desorption spectra regardless of the annealing procedure. The combination of the two techniques in a full in‑situ approach is shown capable to identify the distinct retention behavior of deuterium at different temperatures and in different reservoirs, e.g. located close to the surface and deuterium diffused deeper in the material from a single sample. Simultaneously, protium was detected in small amounts close to the sample surface. Ex-situ scanning electron microscopy analysis confirmed blister formation induced by ion implantation, and a recovery of the initial surface morphological aspect after high temperature annealing, confirming the analogy of our model system to earlier comprehensive ex‑situ studies.
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| 4. |
- Kantre, Karim-Alexandros, et al.
(författare)
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Investigation of the energy loss of I in Au at energies below the Bragg peak
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 450, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- The energy loss of iodine in gold was investigated at energies below the Bragg peak. With the present work, the range of the available experimental data is extended to significantly lower energies, while the nuclear stopping power contribution is taken into account. Experiments were performed on thin film targets in reflection geometry. Electronic stopping cross sections were extracted by different approaches from experimental spectra. The obtained results have been compared to tabulated values from SRIM and previously published experimental data, where available. For all energies the obtained values are consistently higher than predicted by SRIM. Monte Carlo simulations (TRIM) have been performed to study path length distributions and the influence of nuclear stopping on the total energy loss. The results from the calculations indicate that the experimental geometry might be an important factor affecting the observed energy loss due to a selection of specific trajectories.
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| 5. |
- Kantre, Karim-Alexandros
(författare)
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Materials analysis using MeV-ions: fundamental challenges and in-situ applications
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interaction of energetic ions with matter is highly relevant for a wide range of applications. Amongst them, material characterization employing ion beams is widely used due to its capability of high-resolution composition depth profiling. The non-destructive nature of these techniques makes them appealing, although there are still several aspects which can be improved and thus deserve attention. For example, better understanding of energy deposition of ions in matter, can improve simultaneous depth profiling of light and heavy atomic species in a single target. Also, the synthesis of advanced material systems requires complex, multi-step protocols. This situation creates an increased demand for in-situ material characterization, keeping the benefits of ion beam analysis. The present thesis addresses the above mentioned open aspects which are of both fundamental and applied character.First, the energy loss of heavy ions in solid matter, at energies relevant for recoil spectrometry, is investigated. The contribution of inelastic and elastic collisions of heavy ions to the total energy loss as well as the validity of the single scattering assumption are assessed. This analysis is performed by a combination of experiments using different ions and target materials and corresponding Monte Carlo simulations. A non-trivial dependence of elastic losses and trajectory length on probing depth is found. These observations are not accounted for in several common analysis packages and their implications for depth-profiling are discussed.Second, the potential of tracking material modification processes, such as annealing or reactive thin film deposition, in-situ by MeV ion beams is investigated. An experimental setup, SIGMA - Set-up for In-situ Growth, Materials modification and Analysis, was constructed. SIGMA holds equipment for thin film growth, low energy ion implantation, sputtering, annealing and controlled exposure to reactive gases, while several ion beam analytical techniques are available.Within this thesis, two studies associated with the rapidly growing field of sustainable energy were performed illustrating the capabilities of SIGMA. First, the growth of photochromic yttrium oxyhydride thin films was monitored in-situ. This study established the complete synthesis path of this material class and furthermore showed that the initial oxidation rate affects the post oxidation rate and the persistence of the photochromic effect. In a second investigation, deuterium implantation in tungsten was combined with in-situ ion beam analysis and thermal desorption spectroscopy to track the deuterium release during annealing. The employed combination of techniques permits to correlate depth-resolved information from ex-situ analysis with data accessible at operating future fusion devices.
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| 6. |
- Kantre, Karim-Alexandros, et al.
(författare)
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SIGMA : A Set-up for In-situ Growth, Material modification and Analysis by ion beams
- 2020
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 463, s. 96-100
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Tidskriftsartikel (refereegranskat)abstract
- We present a set-up for in-situ non-destructive high-resolution composition depth profiling by ion beams developed at the 5 MV 15 SDH-2 Tandem accelerator at the Angstrom laboratory at Uppsala University. The scattering chamber allows thin film deposition, modification and characterization which can be used to study the very initial stages of near-surface processes such as thin film growth, oxidation, annealing or ion implantation. We describe the available instrumentation with its specifications in detail and present experimental applications, i.e. the characterization of reactive in-situ thin film growth and controlled oxidation, as well as a study of ion implantation and the impact of thermal annealing and surface oxidation on the implantation profiles.
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| 7. |
- Kantre, Karim-Alexandros, et al.
(författare)
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Synthesis and in-situ characterization of photochromic yttrium oxyhydride grown by reactive e--beam evaporation
- 2020
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 186, s. 352-356
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Tidskriftsartikel (refereegranskat)abstract
- We report on controlled growth of photochromic yttrium oxyhydride thin films monitored by in-situ composition depth profiling. Films were grown by reactive e(-)-beam evaporation and subsequently oxidized, while simultaneously tracking the oxygen and hydrogen concentrations. Sample composition and photochromic response were characterized in-situ using non-destructive ion beam analysis and image analysis, respectively - as well as complementary ex-situ ion beam methods, X-ray diffraction and optical spectrophotometry. We show that photochromic yttrium oxyhydride can be grown as yttrium dihydride, which is then oxidized to O/H ratios triggering the photochromic response.
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| 8. |
- Kokkoris, M., et al.
(författare)
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Benchmarking the evaluated proton differential cross sections suitable for the EBS analysis of natSi and 16O
- 2017
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 405, s. 50-60
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Tidskriftsartikel (refereegranskat)abstract
- The evaluated proton differential cross sections suitable for the Elastic Backscattering Spectroscopy (EBS) analysis of Si-nat and O-16, as obtained from SigmaCalc 2.0, have been benchmarked over a wide energy and angular range at two different accelerator laboratories, namely at N.C.S.R. 'Demokritos', Athens, Greece and at Ruder Boskovic Institute (RBI), Zagreb, Croatia, using a variety of high-purity thick targets of known stoichiometry. The results are presented in graphical and tabular forms, while the observed discrepancies, as well as, the limits in accuracy of the benchmarking procedure, along with target related effects, are thoroughly discussed and analysed. In the case of oxygen the agreement between simulated and experimental spectra was generally good, while for silicon serious discrepancies were observed above E-p,E-lab = 2.5 MeV, suggesting that a further tuning of the appropriate nuclear model parameters in the evaluated differential cross-section datasets is required.
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