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Different studies reveal the behaviour of Ta alloying to decrease deuterium retention in tungsten bulk materials aiming to be used for nuclear fusion applications. In this work, W and W-5 %Ta coatings were produced via magnetron sputtering techniques. The elemental composition of the samples and the spread of Ta in the W lattice was confirmed by GDOES, PIXE and by μ-PIXE, respectively. Sets of W and W-Ta coatings were simultaneously irradiated with a single 2H2+ or with sequential 4He+/2H2+ ion beam implantations using incident energies of 30 keV and ion fluences of 5 × 1017 ion/cm2. The irradiated samples were analysed by NRA/RBS and by ToF-ERDA to quantify the retained deuterium and helium amounts. The results reveal significantly lower contents of both isotopes in W-Ta.

In the presented work, evaluated differential cross section data for the 12C(p,p0)12C reaction calculated by SigmaCalc 2.0 (Gurbich, 2016) were validated using benchmarking procedures. Protons in the energy range from 1.2 to 3.5 MeV were backscattered from a thick glassy carbon target at three different scattering angles: 118°, 150° and 165°. For scattering angles of 150° and 165°, agreement between experimental and simulated spectra was generally good for the investigated energy span. However, at 118°, the simulation underestimates experimental data in the whole measured energy range, indicating that the evaluated differential cross section data are too low. The results are presented in graphical and tabular form, together with the accuracy limits of the benchmarking procedure.

Renewable energies are foreseen as a major energy resource for next generations. Among several energy sources and technologies available, Concentrated Solar Power (CSP) technology has a great potential, but it needs to be optimised, in particular to reduce the costs, with an increase of the operating temperature and long term stability. This goal can be achieved by tailoring the composition and multilayer structure of films. In this work we present and discuss the results obtained from solar absorber coatings based on nitride/oxynitride structures. A four-layer film structure, W/CrAlSiNx(HA)/CrAlSiNxOy(LA)/SiAlOx, was deposited on stainless steel substrates using magnetron sputtering deposition method. Simulations were performed to establish the best spectral properties of the multilayer stacks with optical constants of single layers and film thickness. The elemental analysis was performed using Rutherford Backscattering Spectrometry (RBS) and Time of flight Elastic Recoil Detection Analysis (TOF-ERDA). To assess the thermal stability of the coatings the samples were thermal annealed at 400°C, in air, and at 600°C, in vacuum. The results obtained by RBS and TOF-ERDA reveal good oxidation resistance and thermal stability. Also, the optical measurements confirm the potential of these materials for the use in CSP technology., The authors acknowledge the support of FCT in the framework of the Strategic Funding UID/FIS/04650/2013 and the financial support of FCT, POCI and PORL operational programs through the project POCI-01-0145-FEDER-016907 (PTDC/CTM-ENE/2882/2014), co-financed by European community fund FEDER. K. Arstila acknowledges the support by Academy of Finland Center of Excellence in Nuclear and Accelerator Based Physics (Ref. 251353).

Differential cross sections for proton induced γ-ray emission from the reactions 23Na(p, p′γ)23Na (Eγ = 441 and 1636 keV) and 23Na(p, α′γ)20Ne (Eγ = 1634 keV) were measured for proton energies from 1.0 to 4.1 MeV in five different ion beam laboratories. Backscattered protons were collected simultaneously for normalization purposes, avoiding the measurement of the absolute values of the collected beam charge. The overall uncertainty was estimated to be around 7–8% for the cross section of the 441 keV γ-ray line from the 23Na(p, pγ1-0)23Na reaction, and of 8–12% for the cross section of the 1634–1636 keV γ-ray lines from the 23Na(p, αγ1-0)20Ne and 23Na(p, pγ2-1)23Na reactions. To check the possible anisotropy of the emitted 441 keV γ-ray, angular distribution measurements were performed at 1292, 1468, 1931, 2083 and 2851 keV proton energy, where sharp and well separated resonances occur in the excitation function ; moreover, in the energy range from 2.5 to 4.1 MeV proton energy, differential cross sections at 0°, 45° and 90° were measured as well.

In the present paper results concerning the implementation of the Glow Discharge Optical Emission Spectrometry (GDOES) for measure the He depth profile within W coatings are given. The He emission line situated at 587.5 nm was used in this respect. W coating containing He up 10 at.% and with thickness of 5 μm have been obtained by Combined Magnetron Sputtering and Ion Implantation (CMSII) method. The coatings structure and morphology was investigated using Scanning Electron Microscopy (SEM) measurements. The He retention within the coatings was evaluated by using Thermal Desorption Spectroscopy (TDS). Time-of-Flight Elastic Recoil Detection Analysis (TOF ERDA) measurements has been used to determine chemical composition of the coatings. Results of TOF-ERDA measurements results were used to calibrate the GDOES equipment. Using these data the GDOES depth profiles of the He within W coatings have been obtained.

Particle-Induced Gamma-ray Emission (PIGE) is a powerful analytical technique that exploits the interactions of rapid charged particles with nuclei located near a sample surface to determine the composition and structure of the surface regions of solids by measurement of characteristic prompt γ rays. The potential for depth profiling of this technique has long been recognized, however, the implementation has been limited owing to insufficient knowledge of the physical data and lack of suitable user-friendly computer codes for the applications. Although a considerable body of published data exists in the nuclear physics literature for nuclear reaction cross sections with γ rays in the exit channel, there is no up-to-date, comprehensive compilation specifically dedicated to IBA applications. A number of PIGE cross-section data had already been uploaded to the Ion Beam Analysis Nuclear Data Library (IBANDL) ( http://www-nds.iaea.org/ibandl ) by members of the IBA community by 2011, however a preliminary survey of this body of unevaluated experimental data has revealed numerous discrepancies beyond the uncertainty limits reported by the authors. Using the resources and coordination provided by the IAEA, a concerted effort to improve the situation was made within the Coordinated Research Project on the Development of a Reference Database for PIGE spectroscopy, from 2011 to 2015. The aim of the CRP was to create a data library for Ion Beam Analysis that contains reliable and usable data on charged particle γ-ray emission cross sections that would be made freely available to the user community. As the CRP has reached its completion, we shall present its main achievements, including the results of nuclear cross-section evaluations and the development of a computer code that will become available to the public allowing for the implementation of a standardless PIGE technique.

Raman microscopy is one of the methods that could be used for future post-mortem analyses of samples extracted from ITER plasma facing. This study shows that this technique is useful for studying tungsten-based materials containing impurities including oxides and nitrides. Here, we apply pulsed laser deposition and DC argon glow discharges to produce tungsten-containing synthetic films (compact, porous) and nanoparticles and investigate the influence of their morphology on the measured Raman spectra. The amounts of oxygen and/or nitrogen in the films are also investigated. Comparative data are obtained by X-ray Photoelectrons Spectroscopy, Atomic Force Microscopy, Electron Microscopies (Scanning and Transmission), Energy Dispersive X-ray spectroscopy, Time-of-Flight Elastic Recoil Detection Analysis. The power density of the laser beam used to perform Raman microscopy is varied by up to 4 orders of magnitude (0.01-20 mW/$\mu$m 2) to investigate thermal stability of films and nanoparticles. As a first result, we give evidence that Raman microscopy is sensitive enough to detect surface native oxides. Secondly, more tungsten oxides are detected in porous materials and nanoparticles than in compact films, and the intensities of the Raman band correlate to their oxygen content. Thirdly, thermal stability of these films (i.e. structural and chemical modification under laser heating) is poor when compact films contain a sufficiently large amount of nitrogen. This finding suggests that nitrogen can be substituted by oxygen during Raman laser induced heating occurring in ambient air. Finally, our methodology can be used to rapidly characterize morphology and chemistry of the samples analyzed, and also to create oxides at the micrometer scale. keywords: PLD, Raman spectroscopy, tungsten oxide, tungsten nitride, plasma wall interaction, laser heating, post-mortem analysis 2, Comment: Nuclear Fusion, IOP Publishing, 2020

The present work investigates the potential of ion beam analysis (IBA) techniques such as the Rutherford backscattering spectrometry (RBS) and particle induced X-ray emission (PIXE) using helium ions to provide quantitative in-depth elemental analysis of various types of Cu(In,Ga)Se 2 thin films. These films with a thickness of about 2 μm are used as absorber layers in photovoltaic devices with continuously increasing the performance of this technology. The preparation process generally aims to obtain an in-depth gradient of In and Ga concentrations that optimizes the optoelectronic and electrical properties of the solar cell. The measurements were performed at directly accessible single or double layered CIGS absorbers and at buried absorbers in completed thin film solar cells. The IBA data were analyzed simultaneously in order to derive best fitted profiles that match all experimental RBS and PIXE spectra. For some samples elemental profiles deduced form synchrotron based, reference free grazing incidence X-ray fluorescence analysis were compared with the IBA results and an overall good agreement was observed within quoted uncertainties.

Dubrovnik was an important trade city throughout the medieval and post-medieval time period, maintaining its own glass production from the 14th to the 16th century. Unfortunately, Dubrovnik glass discoveries have not been well investigated up until now, except via archival data in large data analyses. In the following work, we will shed new light on the glass material found in this region, which has diverse origins, chronology, typology and style. Medieval and post- medieval glass finds (10th/12th–18th centuries) discovered during archaeological excavations in Dubrovnik and the Dubrovnik region were analysed using particle- induced X-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE), which revealed three main compositional groups: natron glass, plant-ash glass and potash glass. This demonstrates the important commercial links present between Dubrovnik and other major glass-making centres.

The 9 Be( 3 He, p i ) 11 B cross sections for i = 0,1,2,3 at an angle of 135° in the energy range 1–2.5 MeV have been measured using two thin films with different Be thickness at selected energies. The new data extend previous results, that only existed at 90°, 120° and 150° angles, and down to 1.8 MeV, which prevented use of this reaction for samples containing Be at larger depths.

In this work we present differential cross sections for γ-ray emission from the reactions 19F(p,p′γ)19F (Eγ = 110, 197, 1236 and 1349 + 1357 keV), 24Mg(p,p′γ)24Mg (Eγ = 1369 keV) and 25Mg(p,p′γ)25Mg (Eγ = 390, 585 and 975 keV). Differential cross sections were measured for proton energies from 1.95 to 3.05 MeV with a 15 keV step and beam energy resolution of 0.06%. Thin reference standard, 54.1 μg/cm2 of MgF2 deposited on thin Mylar foil with additionally evaporated 4 nm Au layer, was used as a target. The γ-rays were detected by a 20% relative efficiency HPGe detector placed at an angle of 135° with respect to the beam direction, while the backscattered protons were collected using silicon surface barrier detector placed at the scattering angle of 165°. Obtained cross sections were compared with the previously measured data available from the literature.

Plasma-wall interactions have been studied in the full-W ASDEX Upgrade during its dedicated helium campaign. Relatively clean plasmas with a He content of >80% could be obtained by applying ion cyclotron wall conditioning (ICWC) discharges upon changeover from D to He. However, co-deposited layers with significant amounts of He and D were measured on W samples exposed to ICWC plasmas at the low-field side (outer) midplane. This is a sign of local migration and accumulation of materials and residual fuel in regions shadowed from direct plasma exposure albeit globally D was removed from the vessel. When exposing W samples to ELMy H-mode helium plasmas in the outer strike-point region, no net erosion was observed but the surfaces had been covered with co-deposited layers mainly consisting of W, B, C, and D and being the thickest on rough and modified surfaces. This is different from the typical erosion-deposition patterns in D plasmas, where usually sharp net-erosion peaks surrounded by prominent net-deposition maxima for W are observed close to the strike point. Moreover, no clear signs of W nanostructure growth or destruction could be seen. The growth of deposited layers may impact the operation of future fusion reactors and is attributed to strong sources in the main chamber that under suitable conditions may switch the balance from net erosion into net deposition, even close to the strike points. In addition, the absence of noticeable chemical erosion in helium plasmas may have affected the thickness of the deposited layers. Retention of He, for its part, remained small and uniform throughout the strike-point region although our results indicate that samples with smooth surfaces can contain an order of magnitude less He than their rough counterparts.

Tantalum oxide is used in a variety of applications due to its high bandgap, high-K and high index of refraction. Unintentional impurities can change properties of tantalum oxide, and heavy ion elastic recoil detection is a method that can play a fundamental role in the quantification of those impurities. Furthermore, tantalum oxide is frequently part of the samples that also include other materials, which are often analysed with ion beam techniques. However, there are very few reported stopping power measurements for tantalum oxide, and data analysis relies not only on interpolation from a sparse data base but also on the Bragg rule. As is well known, the Bragg rule is often inaccurate for oxides, particularly when the difference in atomic numbers of the involved elements is very large as is case for Ta2O5. We have used a bulk method, previously developed by us and applied successfully to other systems, to determine experimentally the stopping power of tantalum oxide for three different ion types: C, O and Cl. In the present paper the results of our measurements and bulk method analysis are presented.

The structure, thermal stability, composition, morphology, and electrical properties of bixbyite-Ta 2 N 3 films are investigated by combining experimental characterization and ab initio calculations. Ta 2 N 3 films were grown by magnetron sputtering in a pure N 2 atmosphere and subsequently annealed. The as grown film consists of poorly ordered bixbyite-Ta 2 N 3 with stretched unit cell due to the excess of N atoms (N/Ta atomic ratio 2.05) which is mostly within the Ta 2 N 3 nanocrystals. Upon annealing at 450 °C, the excess N atoms migrate to the grain boundaries, the cell parameter reduces and the crystallinity improves. At higher annealing temperatures, the N atoms additionally out diffuse from the films, which results in a decrease of the N/Ta ratio to 1.38 at 950 °C. The Ta 2 N 3 phase is stable up to 850 °C where it transforms into fcc δ-Ta 0.75 N. The resistivity of the as grown film is high (34 Ω cm) and then drastically reduces after annealing at 450 °C (91 mΩ cm). At higher annealing temperatures, the resistivity further decreases (5 mΩ cm at 750 °C), indicating that Ta 2 N 3 is a conductor. We used the percolation theory to quantitatively describe the resistivity variation of the annealed films. Our explanation of the resistivity behavior is supported by ab initio calculations of the electronic structure of Ta 2 N 3 , where we found that the Fermi level is within the conduction band. We also found a band gap below the Fermi level and estimated the optical absorption onset energy to be about 2 eV.

In the present work we investigate effects ofMeVheavy ions (from 0.4 MeVXe to 15 MeVSi) on regularly ordered nanoparticle (NP) lattices embedded in amorphous alumina matrix. These nanostructures were produced by self-assembling growth using magnetron-sputtering deposition. From grazing incidence small-angle x-ray scattering measurements we have found that the usedMeV heavy ions do not change the NPsizes, shapes or distances among them. However, ions cause a tilt of the entire NP lattice in the direction parallel to the surface. The tilt angle depends on the incident ion energy, type and the applied fluence and a nearly linear increase of the tilt angle with the ion fluency and irradiation angle was found. This way,MeV heavy ion irradiation can be used to design custom-made NPlattices. In addition, grazing incidence small-angle x-ray scattering can be effectively used as a method for the determination of material redistribution/shift caused by the ion hammering effect. For the first time, the deformation yield in amorphous alumina was determined for irradiation performed at the room temperature. Iva Bogdanovic Radovic

GaN and other group III nitrides based alloys are important materials in optoelectronic and electronic devices, including high-brightness blue and white LEDs, multi-junction solar cells, high-frequency transistors, and THz emitters. Unintentional impurities can be present, with a strong influence in the properties of these materials. These impurities are often light elements such as H, C, or O, and an ion beam analysis technique such as heavy ion elastic recoil detection analysis can play a fundamental role in their quantification. However, to our knowledge stopping powers in GaN have not yet been measured, and data analysis relies on using the Bragg rule, which is often inaccurate. We have used a bulk method, previously developed by us and applied successfully to other systems, to determine experimentally the stopping power of 4He, 12C and 16O in GaN, in the energy ranges 0.6–2.3, 0.9–14.9, and 0.6–14.9 MeV, respectively. The results of our measurements and bulk method analysis are presented.

The cross-sections for the elastic scattering of alphas from natural nitrogen were measured at three laboratory scattering angles: 118°, 150° and 165° at non-Rutherford scattering energies from 2.5 to 4.0 MeV. Experimental data obtained in this work, together with all previously published data, were used for the cross-section evaluation. Model calculations with comparison and fitting to the experimental data were used for the evaluation of the cross-section. As a result of the work, the recommended cross-sections for scattering of alphas from nitrogen have been produced in the energy region of 1.6–4.6 MeV.

Thin films based on Cu(In,Ga)Se 2 are used as absorber cells in photovoltaic devices. In and Ga graded depth profiles are designed to optimize the solar cell performance. Simultaneous Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-ray Emission (PIXE) with 3 MeV 4 He ions were used in conjunction to determine the depth profile of all the heavy elements in Cu(In,Ga)Se 2 absorbers and complete solar cells. The RBS and PIXE data from one sample were analyzed synergistically, providing reliable depth profiles that satisfy all the data collected. An uncertainty analysis was done, probing the sensitivity of the analysis to different assumptions. The analytical possibilities of the combined RBS/PIXE alpha beam measurements of the CIGSe thin film solar cells, as well as the uncertainties induced in the quantitative methodology are discussed and critically assessed.

The popular stopping power interpolative schemes require experimental data to be developed. Where the data bases are sparse, with few experiments available, interpolations can be more inaccurate. This is the case for the stopping of heavy ions, where even for important targets such as Si there is a need for more measurements. For compounds, the situation is even worse with very few measurements available. In particular, the stopping in oxides and nitrides often deviates significantly from what would be expected using the Bragg’s rule. We apply a method that uses bulk or thick film samples to determine the stopping power of 11B in Si and TiO2. The method, which relies on Bayesian inference analysis of RBS spectra obtained at different energies, has been previously validated by verifying the results obtained in the well-known system 4He in Si.

In this work we have studied the influence of thermal annealing on the structural and electrical properties of W-Ti thin films, deposited on n-type (100) silicon wafers. The films were deposited by d.c. sputtering from a 90:10 wt.%W-Ti target, using Ar ions, to a thickness of similar to 170 nm. After deposition the samples were annealed at 400 to 700 degrees C for 60 min, in a nitrogen ambient. Structural characterizations were performed by X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). A four-point probe was used for electrical characterization. It was found that the as-deposited films exhibit a polycrystalline structure in the form of columnar grains (2050 nm in diameter). Only b.c.c. W phase could be registered in the films, while any presence of crystalline Ti was hindered in XRD and electron diffraction patterns. Annealing at up to 600 degrees C resulted in an increase of the mean grain size in the films, and a decrease of their sheet resistance. For these annealing temperatures we did not register any interaction at the W-Ti/Si interface. However. upon annealing at 700 degrees C, a progressed interaction between the film and the substrate occurred. Structural analyses suggest the formation of both W and Ti silicides. The estimated thickness of the formed metal-silicide layer is approximately 125 nm. Sheet resistance increased rapidly after annealing at 700 degrees C, because a large portion of the original metallic film was consumed in the reaction with silicon. (C) 2009 Elsevier B.V. All rights reserved. Symposium on Protective Coatings and Thin Films held at the 2009 E-MRS Spring Meeting, Jun 08-12, 2009, Strasbourg, France

The installation of a new 1.0 MV Tandetron accelerator and a recent upgrade of the 6.0 MV Tandem Van de Graaff accelerator increased the application possibilities of the Zagreb ion microbeam system. Several ion sources enable now the selection of a wide variety of ions. Most of them can be focused by the existing microprobe system. Sample positioning tools and new scanner control options are implemented in the new generation of SPECTOR data acquisition system. Details of the upgrades are presented.

In the literature several elastic scattering cross-sections data sets are available for protons on 10B and 11B at energies and scattering angles suitable for elastic backscattering spectrometry (EBS) analysis. However, agreement between these different data sets is generally poor, with systematic differences up to 20%, well beyond the stated absolute uncertainties. To resolve the conflict between the different data sets in the absence of the evaluated cross-section data, a benchmark experiment was performed. Proton backscattering spectra were obtained with a thick uniform B4C target at beam energies in the range of 2.0–4.0 MeV and at different scattering angles, followed by a standard direct simulation with the SIMNRA code using the available experimental cross-section data. As a result, recommendation on the most appropriate data set to be used in proton EBS analysis of boron is given.

Ge quantum dots embedded in SiO 2 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 °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 °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.

Elastic recoil detection analysis (ERDA) using a He ion beam and a detector with a stopper foil is a common technique for the analysis of hydrogen and its isotopes. A good alternative to He ERDA, for laboratories not equipped with a He ion source, is the use of Li ions. These may be beneficial because of an increased depth resolution due to the larger stopping power and higher cross-section for hydrogen recoils. Deviations from the Rutherford cross-section at 30° can be expected for energies above 2.9 MeV. However, as far as the authors know, ERDA cross-sections for H with Li ions at energies above this critical energy are not available in the literature. Therefore, differential proton recoil cross-sections for incident 7 Li ions were measured in this work in an energy range between 2.28 and 5.70 MeV at recoil angles of 30° and 45°. Thin melamine foils (∼50 μg/cm 2 ) evaporated on thin Al (∼50 μg/cm 2 ) backings were used for the measurements. Special care was taken to monitor hydrogen loss during the measurement.

Hydrogenated amorphous silicon solar cells were studied by the use of Rutherford backscattering and elastic recoil detection analysis. By the application of different ion types, energies and geometry, the layered structure of solar cells as well as their hydrogen content were determined. Results were correlated to optical and electrical properties of samples and the difference between the two types of solar cells, with “higher” and “lower efficiency”, is discussed.

The differential cross-sections for elastic scattering of 4 He ions by carbon atoms were measured at scattering angles of 30°, 45°, 60°, 135° and 150° in the energy range from 2 to 4.8 MeV. Up to now mostly data for angles larger than 150° were published in the literature. A thick carbon target with a thin evaporated Cu layer on the surface was used for the measurement. The number of impinging projectiles was obtained from the He ions scattered by the Cu layer assuming Rutherford cross-sections. The carbon scattering cross-sections were then obtained from comparison of measured He energy spectra with the simulated ones. Above 2 MeV all evaluated cross-sections become non-Rutherford. Deviations from Rutherford cross-sections are about 50% for 30° scattering angle and amount up to a factor 30 for 150° scattering angle. The measured experimental cross-sections were compared with the calculated theoretical cross-sections and already published data. Satisfactory agreement was obtained for all measured scattering angles and energies.

The low-cost polycrystalline substrates used in solar cell production suffer from a high concentration of impurities and defects. The influence of the particular defect on the electrical properties of material is important information and can be obtained only by the application of complementary characterisation techniques. The ion beam induced charge collection (IBICC) technique provides information about the spatial distribution of imperfections in charge collection, while the origin of these imperfections is not known. Therefore, various samples of edge-defined film-fed grown (EFG) and Czochralski (Cz) silicon were also analysed by deep level transient spectroscopy (DLTS), identifying the most important deep levels in the band gap. The influence of twin boundaries in EFG samples and high oxygen content of Cz material on the IBICC results are discussed as well as the IBICC-induced defects in test samples.

Proton diAerential recoil cross-sections were measured for impact of He ions in the energy range from 2.5 to 4.5 MeV and for recoil angles from 30∞ to 60∞. For the first time, H recoil cross-sections at angles from 45∞ to 60∞ are reported. All the measured cross-sections, except those for 60∞, deviate from the Rutherford cross-sections. Thin melamine foils (50 lg=cm 2 ) evaporated on50 lg=cm 2 thick Cu were prepared as targets. Two surface barrier detectors positioned at forward angles were used to detect the recoiled and scattered atoms. One detector was kept all the time at 40∞ and was used to measure the loss of H due to irradiation. The experimental results were compared with the other available experimental data for lower recoil angles and a good agreement is found. A comparison is also made with the theoretical calculations obtained by fitting the phase shifts of the kinematic inverse reaction using the principle of detailed balance. Again an agreement is found for low recoil angles, but for 55∞ and 60∞ the experimental cross-sections are significantly smaller than the theoretical values. ” 2001 Elsevier Science B.V. All rights reserved.

A study of morphological and composition changes of the (8(Al/Ti)/Si) system induced by laser pulses in different ambient conditions is presented. The effects of an Er, Yb, Cr-Glass laser, operating at 1540 nm wavelength with pulse duration of 44 ns, on a complex target were investigated. Irradiation of 8(Al/Ti)/Si was carried out at intensities of 5.9 and 9.5 x 10(11) W m(-2) in air, water and ethanol. The laser-induced morphological and composition modifications have shown dependence on applied intensities, number of laser pulses and ambient conditions. The following morphological changes were observed: (i) intense surface melting of the thin film and Si-substrate; (ii) ablation/exfoliation of the 8(Al/Ti) multilayer thin film from Si, (iii) appearance of hydrodynamic features such as resolidified material, and (iv) formation of crater at multi-pulse action. The formation of parallel periodic surface structure was only occurring in single pulse air-assisted modification. Analysis of the composition revealed that laser modification induced intermixing between the components of individual Al and Ti layers with potential formation of AlTi intermetallic compounds. (C) 2013 Elsevier Ltd. All rights reserved.

Laser-induced periodic surface structures (LIPSSs) and chemical composition changes of Ti-based nanolayered thin films (Al/Ti, Ni/Ti) after femtosecond (fs) laser pulses action were studied. Irradiation is performed using linearly polarized Ti:Sapphire fs laser pulses of 40 fs pulse duration and 800 nm wavelength. The low spatial frequency LIPSS (LSFL), oriented perpendicular to the laser polarization with periods slightly lower than the irradiation wavelength, was typically formed at elevated laser fluences. On the contrary, high spatial frequency LIPSS (HSFL) with uniform period of 155 nm, parallel to the laser light polarization, appeared at low laser fluences, as well as in the wings of the Gaussian laser beam distribution for higher used fluence. LSFL formation was associated with the material ablation process and accompanied by the intense formation of nanoparticles, especially in the Ni/Ti system. The composition changes at the surface of both multilayer systems in the LSFL area indicated the intermixing between layers and the substrate. Concentration and distribution of all constitutive elements in the irradiated area with formed HSFLs were almost unchanged. (C) 2013 AIP Publishing LLC.

We used a thin film method with Bayesian inference data analysis to determine the 13C(p,p)13C cross section in the energy range 0.8–2.43 MeV, at scattering angles 140° and 160°. The accuracy of the results was also determined, including all sources of error. The cross section determined at 140° was benchmarked at energies around the 1.462 MeV resonance. The new data presented were then used, together with previously existing data from the literature, to perform an evaluation of the 13C(p,p)13C cross section.

Thin films of tantalum nitride (Ta–N) have been prepared by reactive magnetron deposition under various nitrogen partial pressures pN2=0-1 and subsequently annealed (Ta = 450–950 °C). The structure, density, composition and electrical resistivity of the prepared films were systematically investigated. A pN2-Ta phase map was constructed from the results of structural analysis. With increasing of pN2 from 0 to 0.2, a single-phase or two-phase mixture films of tetragonal Ta, Ta2N (Ta > 450 °C), eps-TaN (Ta > 850 °C), theta-TaN (Ta > 850 °C) and fcc delta-TaN are sequentially observed. For pN2 = 0.25–0.45, the as grown and annealed films exhibit delt-TaN structure. Amorphous films grown in the pN2 = 0.45–0.75 range crystallize as cubic Ta2N3 upon annealing at Ta > 650 °C or as delt-TaN at Ta > 850 °C. A cubic Ta2N3 is grown at highest pN2 (>0.85), which decomposes to delt-TaN at Ta > 850 °C. The N /Ta atomic ratio in the film linearly increases for pN2 = 0–0.5, ranging from 0 to 2.1, while the mass density monotonously decreases with pN2. Upon annealing, a part of N atoms outdiffuses from the films deposited at pN2 > 0.3. The electrical resistivity strongly depends on both pN2 and Ta. However, in the as grown and annealed delt-TaN films the resistivity was of the order of 100–1000 µOhmcm. In these films, a correlation between the resistivity and the average number of defects (Ta vacancies and N atom excess) is observed. Finally, the influence of thermally introduced oxygen on the films resistivity has been revealed.

In this work we deposited a series of hydrogenated amorphous carbon (a-C:H) films and nitrogen-doped a-C:H films on silicon substrates using an ion-beam-deposition technique called anode layer source. We used different discharge voltages, which influence the sp 2 /sp 3 carbon hybridization ratio, and we also varied the N 2 -to-C 2 H 2 flow ratios. The composition was analysed by elastic recoil detection analysis (ERDA), to determine the hydrogen content, in combination with Rutherford backscattering spectroscopy (RBS), for the heavier elements. An additional set of experiments was conducted by time-of-flight (TOF) ERDA, which gives information not only about the hydrogen content but also about the content of other lighter elements (C, N and O) in the sample. The influence of the deposition parameters on the chemical composition and the structure of the films (studied by Raman spectroscopy) was thus evaluated. The discharge voltage did not have a measurable effect on the composition (but a decisive one on the structure), while the nitrogen flow variations were clearly proven in respective trends in the chemical composition and structure variations.

Thin granular films of charge density wave (CDW) system K0.3MoO3 were prepared by pulsed laser deposition and investigated by various standard characterization methods such as GI-XRD, electric transport, TOF-ERDA, AFM and UV–visible spectroscopy. While all these methods indicate that the thin films consist of nanometer grains of K0.3MoO3, it is only the non-destructive femtosecond time-resolved spectroscopy (fsTRS) that demonstrates the charge density wave nature of the ground state and therefore proves directly the presence of K0.3MoO3. Furthermore, the comparison of the fsTRS data obtained in thin films and in single crystals shows the reduction of the charge density wave transition temperature and of the photoinduced signal strength in granular thin films with respect to single crystals, which is attributed to the granularity and crystal growth morphology. Our results establish fsTRS technique as the essential tool for the detection and characterization of complex ground states in nano-sized systems.

Stopping powers play a fundamental role in Ion Beam Analysis, because they are essential for the depth profiling capability of Rutherford backscattering and elastic recoil detection analysis, and also the depth range probed by other techniques such as particle induced X-ray emission. Any inaccuracy in the stopping powers are directly reflected in the depth scales determined. In practice, IBA relies on data bases or interpolative schemes such as SRIM or MSTAR, which depend on existing data. For compounds and for heavy ions, the data bases are scarce, and inaccuracies can be large. Titanium dioxide is a semiconductor used in photocatalytic thin films and as a UV absorber material. Light dopants and impurities change its properties and heavy ion ERDA is an ideal technique to study them. However, to our knowledge no measurements have yet been made of the stopping power of heavy ions in TiO 2 . We used a bulk method, previously developed by us and applied successfully to other systems, to determine experimentally the stopping power of 4 He, 12 C and 16 O in TiO 2 thin films grown on glassy carbon, in the energy ranges 0.1–2.4, 0.6–9.9, and 0.3–14.9 MeV, respectively. The results of our measurements are presented.

In this work, three-dimensional (3D) structures were produced in PMMA and CR-39 polymer resists using a carbon ion microbeam. To investigate possible advantages of heavy ions compared to the well-established proton beam lithography, the same resist materials were also irradiated with protons that had a range in the materials studied here similar to that of carbon ions. The microstructures produced in different resists were analysed after chemical etching. The quality of the bottom and side walls of the structures produced by protons and carbon ions were compared using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that, for the resist materials tested, lithographic structures made with the 8 MeV carbon beam had more rough lateral and bottom surfaces compared to those made with 0.6 MeV proton beam lithography.

Group III nitrides such as InN, GaN, and their alloys are increasingly important in a host of optoelectronic and electronic devices. The presence of unintentional impurities is one of the factors that can strongly affect the electronic properties of these materials, and thus ion beam analysis techniques can play a fundamental role, in particular heavy ion elastic recoil detection analysis tracing and quantifying these contaminations. However, stopping powers in InN and GaN have not yet been measured, and data analysis relies on using the Bragg rule, which is often inaccurate. We have used a bulk method, previously developed by us and applied successfully to other systems, to determine experimentally the stopping power of several ions in InN. The results of our measurements and bulk method analysis are presented.

During the last years, femtosecond time-resolved spectroscopy (fsTRS) has become an important new tool to investigate low energy excitations in strongly correlated systems. By studying energy relaxation pathways linking various degrees of freedom (e.g., electrons, spin, or lattice), the interaction strengths between different subsystems can be deduced. Here we report on yet another application of fsTRS, where the technique is used to unambiguously determine the nature of the ground state in granular thin films of a prototype charge density wave system blue bronze, K0.3MoO3. These, potassium blue bronze, films, obtained for the first time ever, have been prepared by pulsed laser deposition and investigated by various standard characterization methods. While the results of all used methods indicate that the thin films consist of nanometer grains of K0.3MoO3, it is only the non-destructive fsTRS that demonstrates the charge density wave nature of the ground state. Furthermore, the comparison of the fsTRS data obtained in thin films and in single crystals shows the reduction of the charge density wave transition temperature and of the photoinduced signal strength in granular thin films in respect to single crystals, which is attributed to the granularity and crystal growth morphology.

The cross sections for the elastic scattering of protons from natural nitrogen at non-Rutherford scattering energies were measured at three laboratory scattering angles: 118°, 150°, and 165°. The experimental data were parametrized in the framework of nuclear physics models. A benchmark experiment was performed in order to prove that the excitation functions obtained in the present work can be used to adequately simulate the yield from a thick target containing nitrogen.

With intention to be used for the 3D analysis of hydrogen, a new ion-induced electron emission (IEE) ERDA system has been installed on the nuclear microprobe. A better depth resolution has been obtained with IEE particle identification system when compared to conventional ERDA systems that use stopping foil. Spectra of the forward scattered ions as well as the recoiled atoms are collected using the same particle detector. This simplifies normalization needed for quantitative analysis without the use of an additional detector. However, well defined but rather small solid angle of the IEE detector requires higher ion beam currents if sufficient sensitivity for H detection needs to be achieved. High beam currents focused to several micrometer spot size lead to rather high current densities and increased probability of H loss from the sample, which may limit the achievable sensitivity. By positioning IEE ERDA system at 45° instead of 30°, as well as by using heavier ions (O ions instead of He), two orders of magnitude better sensitivity can be obtained without a significant deterioration of depth resolution due to the increased recoil cross-section. In this work, several different sample types containing H have been studied. The capabilities of system for 3D imaging of H in samples have been demonstrated.

In this paper, elastic recoil detection (ERD) measurements at recoil angle of 60 degrees using ion-induced electron emission (IEE) for particle identification are presented. In our IEE system for particle identification, recoiled target atoms and scattered projectiles penetrate a set of thin carbon foils before their energy is analyzed in a solid state detector. Particle identification is based on the fact that the total number of electrons emitted from the foils depends on the particle nuclear charge. This method is characterized by its low minimum detectable energy, which stimulated us to study ERDA at 60 degrees. Due to collision kinematics and due to the angular dependence of the scattering cross-sections, it is expected that the sensitivity can be significantly improved. In this work, the detection efficiency of the IEE particle identification system for H recoils at energies below 1 MeV was determined. LA-ERDA measurements were performed with He-4 and C-12 projectiles using two different types of samples with a well-known amount and depth distribution of H atoms near the surface. Sample 1 consisted of a 50 mu g/cm(2) melamine layer evaporated on a flat Si substrate, sample 2 was a Si wafer with implanted H. Sensitivity and depth resolution were measured using LA-ERDA with a recoil angle of 60 degrees and ERDA with recoil angles of 30 degrees and 45 degrees. The results for different recoil geometries and projectiles are discussed and compared with theoretical predictions.

Iron-tungsten (Fe-W) mixed films were exposed to the low flux deuterium plasma of GyM in order to study the behavior of the sputtering yield with the ion fluence and temperature of the samples. From literature, it is known that an increase of the former lowers the Fe-W layers' sputtering yield as a consequence of the preferential sputtering of Fe leading to an enrichment in W of the outermost layers. An opposite trend was instead found for the latter probably due to the inter-diffusion of Fe and W (effective from 200 degrees C) resulting in the suppression of the W enrichment. Moreover, from 500 degrees C, also W segregation to the surface occurs. What is missing from literature is a systematic investigation of the role of temperature on W enrichment. In this work, dedicated experiments in GyM were carried out to fill this gap. After exposure, W enrichment was evaluated by Rutherford Backscattering Spectrometry (RBS) and inferred from measuring the eroded thickness of the samples using RBS and profilometer. Concerning the Fe-W sputtering yield as a function of fluence, it decreases by a factor of similar to 3 between the lowest (3.0 x 10(22) D+ m(-2)) and the highest fluence (9.0 x 10(23) D+ m(-2)) values considered. The other main result is that, at the lowest fluence, the exposure at room temperature leads to an erosion of the Fe-W samples more pronounced than that associated to the exposure at 500 degrees C. (C) 2017 The Authors. Published by Elsevier Ltd.

W-O deposits with complex morphologies and significant He contents will growth on the surface of plasma facing components exposed to He discharges. To mimic the re/co-deposition process, W-O-He coatings were produced by implanting He+ ions on W films grown by pulsed laser deposition (PLD). The use of appropriate PLD experimental parameters such as Ar or He background atmospheres induces the deposition of porous or amorphous-like W-O structures, respectively. After multiple ion implantation stages using 150 keV, 100 keV and 50 keV incident He+ ion beams with a total fluence of 5 x 1017 ion/cm^2, significant amounts of He were identified in porous coatings by Rutherford backscattering (RBS). Time-of-flight elastic recoil detection (TOF-ERDA) measurements showed that most of the implanted He was already released from the porous coatings five month after implantation while for the case of amorphous ones the He content remains significant at deeper layers and smoothly decrease towards the surface, as result of a different morphology and nanostructure. The proposed method involving PLD and ion implantation seems adequate to produce W-O-He reference samples for fusion investigations., 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 n. 633053