Efficient fabrication of high-density ensembles of color centers via ion implantation on a hot diamond substrate

Nitrogen-Vacancy (NV) centers in diamond are promising systems for quantum technologies, including quantum metrology and sensing. A promising strategy for the achievement of high sensitivity to external fields relies on the exploitation of large ensembles of NV centers, whose fabrication by ion implantation is upper limited by the amount of radiation damage introduced in the diamond lattice. In this works we demonstrate an approach to increase the density of NV centers upon the high-fluence implantation of MeV N2+ ions on a hot target substrate (>550 {\deg}C). Our results show that, with respect to room-temperature implantation, the high-temperature process increases the vacancy density threshold required for the irreversible conversion of diamond to a graphitic phase, thus enabling to achieve higher density ensembles. Furthermore, the formation efficiency of color centers was investigated on diamond substrates implanted at varying temperatures with MeV N2+ and Mg+ ions revealing that the formation efficiency of both NV centers and magnesium-vacancy (MgV) centers increases with the implantation temperature.Comment: 12 pages, 5 figure

Plasma-wall interaction studies within the EUROfusion consortium: Progress on plasma-facing components development and qualification

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.European Commission; Consortium for Ocean Leadership 633053; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Profiling and imaging of forensic evidence – a pan-European forensic round robin study part 1: document forgery

The forensic scenario, on which the round robin study was based, simulated a suspected intentional manipulation of a real estate rental agreement consisting of a total of three pages. The aims of this study were to (i) establish the amount and reliability of information extractable from a single type of evidence and to (ii) provide suggestions on the most suitable combination of compatible techniques for a multi-modal imaging approach to forgery detection. To address these aims, seventeen laboratories from sixteen countries were invited to answer the following tasks questions: (i) which printing technique was used? (ii) were the three pages printed with the same printer? (iii) were the three pages made from the same paper? (iv) were the three pages originally stapled? (v) were the headings and signatures written with the same ink? and (vi) were headings and signatures of the same age on all pages? The methods used were classified into the following categories: Optical spectroscopy, including multispectral imaging, smartphone mapping, UV-luminescence and LIBS; Infrared spectroscopy, including Raman and FTIR (micro-)spectroscopy; X-ray spectroscopy, including SEM-EDX, PIXE and XPS; Mass spectrometry, including ICPMS, SIMS, MALDI and LDIMS; Electrostatic imaging, as well as non-imaging methods, such as non-multimodal visual inspection, (micro-)spectroscopy, physical testing and thin layer chromatography. The performance of the techniques was evaluated as the proportion of discriminated sample pairs to all possible sample pairs. For the undiscriminated sample pairs, a distinction was made between undecidability and false positive claims. It was found that none of the methods used were able to solve all tasks completely and/or correctly and that certain methods were a priori judged unsuitable by the laboratories for some tasks. Correct results were generally achieved for the discrimination of printer toners, whereas incorrect results in the discrimination of inks. For the discrimination of paper, solid state analytical methods proved to be superior to mass spectrometric methods. None of the participating laboratories deemed addressing ink age feasible. It was concluded that correct forensic statements can only be achieved by the complementary application of different methods and that the classical approach of round robin studies to send standardised subsamples to the participants is not feasible for a true multimodal approach if the techniques are not available at one location

Deuterium retention in recrystallized tungsten irradiated with simultaneous deuterium-neon ion beams

Although neon has been considered for impurity seeding in the ITER tungsten divertor, there have been few studies on its effects on deuterium retention in tungsten. We investigate the effects of simultaneous (SIM) D-2.5% Ne ion beam irradiation on D retention in recrystallized W at 300–700K, with 500eV/D+ and 1keV/Ne+ ion energies, and compare to the effects of SIM D-3% He irradiation with 500eV/He+. Thermal desorption spectroscopy (TDS) up to 1473K, nuclear reaction analysis (NRA), and elastic recoil detection analysis (ERDA) are used to measure D, He, and Ne in the specimens. Ne is more effective than He at reducing D retention for higher exposure temperatures, even though less Ne is retained than He. He appears to modify the D TDS spectra peak shapes more than Ne, while He addition leads to increased D trapping within a few µm depth according to NRA. D retention may be reduced due to Ne sputtering, as well as a near surface interaction with Ne which blocks D diffusion past the implantation range and leads to higher surface re-emission. Keywords: Tungsten, Deuterium, Helium, Neon, Retentio

Effects of helium ion irradiation on bubble formation in AlN/TiN multilayered system

The effects of helium ion irradiation on immiscible AlN/TiN multilayered system were studied. The structure consisted of 30 alternate AlN (similar to 8 nm) and TiN (similar to 9.3 nm) layers of a total thickness around 260 nm, deposited on (100) Si substrates by reactive sputtering. The system was then implanted with 30 keV He+ to very high irradiation doses, 1-4 x 10(17) ions/cm(2). Evaluated projected ion range was 153.1 +/- 45.4 nm and maximum displacements per atom for the applied doses from 6 to 24. It was found that the multilayers remained well separated and stable after irradiation to 1 x 10(17) ions/cm(2), which introduces up to 10 at.% of He within the structure. The main effects were agglomeration of He bubbles around the projected ion range, mostly concentrated at the AlN edges of the interfaces, and a slight increase of the mean grain size within the affected zone. Increasing of the ion dose induced further agglomeration of bubbles, splitting of the layers at the interfaces, and final destruction of the structure. The evaluated He content was consistent with the implanted dose up to 2 x 10(17) ions/cm(2). For the highest dose the implanted gas is partially released from the structure. The results can be interesting towards the development of radiation tolerant materials. (C) 2015 Elsevier B.V. All rights reserved.16th International Conference on Thin Films (ICTF), Oct 13-16, 2014, Dubrovnik, Croati

Ion beam synthesis and characterization of Ge nanoparticles in SiO2

Ge quantum dots embedded in SiO2 have been obtained by implantation of Ge ions in the 10(16)-10(17) cm(-2) dose range, followed by post-implantation annealing in the temperature range T-a = 300-1000 degrees C. Using Rutherford back-scattering, grazing incidence X-ray diffraction and grazing incidence small angle X-ray scattering it was found that Ge-QDs are synthesized as discrete, spherical QDs, with radius ranging from 1.7 to 10 nm, depending on dose and T-a. For T-a above 800 degrees C the Ge atom diffusion becomes considerable, leading to a strong increase of both size and size distribution of Ge QDs, but still without sizeable loss of Ge atoms from the implanted layer

Laser-induced surface oxidation of (Ni/Ti)/Si system with picosecond laser pulses

The surface oxidation of Ni/Ti bilayer, deposited on silicon substrate, affected by picosecond Nd: YAG laser radiation has been investigated. Fluence close to the target ablation threshold and multi-pulse laser irradiation regime were applied. Changes in the chemical composition of the formed surface oxide layer were studied by Elastic Recoil Detection Analysis (ERDA) and X-ray photoelectron spectroscopy (XPS). Morphological features analysis, at the oxide surface layer, was monitored, too. Laser modification as-deposited (Ni/Ti)/Si sample with 10 pulses induces a progressed interaction between Ni and Ti layers with the initial surface oxidation and formation of NiTi alloy phase. Progressed intermixing of components was achieved for the irradiation with 50 and more pulses, when all components were quite uniformly distributed to a depth of about 80 nm. An oxide layer was formed at the surface, with the specific combination of the oxide phases depending on the number of accumulated pulses. Changes in the morphological characteristics are reflected in the increase of the mean surface roughness and the generation of a certain number of cavities. These features are decreased with increasing number of pulses, caused by the surface melting and a pronounced mobility of the materials. (C) 2013 Elsevier B.V. All rights reserved

Identification of Synthetic Organic Pigments (SOPs) Used in Modern Artist’s Paints with Secondary Ion Mass Spectrometry with MeV Ions

This work reports on the first systematic study using secondary ion mass spectrometry with MeV ions (MeV-SIMS) for analysis of synthetic organic pigments (SOPs) that can be usually found in modern and contemporary art paints. In order to prove the applicability of the method to different chemical classes of SOPs, 17 pigments were selected for the analyses. The focus was on blue and green phthalocyanines, yellow and red (naphthol AS) azo pigments, red quinacridone, anthraquinone, and diketopyrrolo-pyrrole pigments. Since there are no reference spectra available for this technique, pure pigment powders were measured first to create a database. Simple two-component paint systems were also prepared for testing purposes by mixing synthetic organic pigments with alkyd and acrylic binders. Commercial paints that contain the SOPs with identical C.I. numbers as in the prepared two-component samples were analyzed. All pigments were successfully identified in commercial products in the MeV-SIMS mass spectra through molecular and larger specific fragment ion peaks in the positive-ion mode. The main advantages of MeV-SIMS over other techniques used in SOPs identification, like pyrolysis gas chromatography mass spectrometry (Py-GC/MS), direct-temperature resolved mass spectrometry (DTMS), and laser desorption ionization mass spectrometry (LDIMS), can be summarized as follows: (i) pigments and binders can be detected simultaneously in the same mass spectrum acquired over a short measurement time (up to 500 s), (ii) only small sample flakes are required for the measurements, which are analyzed without any chemical treatment prior to the analyses, (iii) samples are not consumed during the analyses and can be reused for other measurements, e.g., multielemental analysis by other ion beam analysis (IBA) techniques, such as particle-induced X-ray emission (PIXE). Compared to, e.g., Raman spectroscopy, the significant benefit of MeV-SIMS is the exact identification of the SOPs in the paints even if pigments of similar structures are measured