Ion Beam Analysis Research Articles

In-situ, real-time investigation of the formation of oxygen-containing rare-earth hydrides by combining a quartz crystal microbalance and ion beam analysis

We present an in-situ and real-time investigation of the formation of YHO and GdHO thin films grown by reactive e−-beam evaporation. Mass changes were continuously monitored during deposition, oxidation, and illumination using a highly sensitive quartz crystal microbalance, while changes in chemical composition and depth profiles were investigated simultaneously by ion beam analysis. Results highlight the strong reactivity of freshly deposited YHx and GdHx films, even under ultra-high vacuum conditions. Oxidation starts at the surfaces of the films and the oxidation rate is strongly dependent on the O2 pressure. The response of the system under ion beam irradiation and in-situ illumination is also presented and discussed. For the measured mass changes, a quantitative agreement better than 2% was observed between both techniques and demonstrates the consistency and sensitivity of this approach.

The Influence of H Content on the Properties of a-C(W):H Coatings

Diamond-like-carbon “DLC” coatings can be deposited in many different ways, giving a large range of material properties suitable for many different types of applications. Hydrogen content significantly influences the mechanical properties and the tribological behavior of DLC coatings, but its determination requires techniques that are not available in many research centers. Thus, it is important to find alternative indirect techniques, such as Raman spectroscopy or nanoindentation (hardness measurements), which can give comparative and indicative values of the H contents in the coatings, particularly when depositions with a reactive gas flow are being studied. In this work, “DLC” composite coatings with varying H content were deposited via Physical Vapor Deposition (PVD) magnetron sputtering in a reactive atmosphere (Ar + CH4). An Ion Beam Analysis was used to determine the elemental depth profile across the coating thickness (giving both average C:W:H ratios and film density when combined with profilometer measurements of film thickness). The hardness was evaluated with nanoindentation, and a decrease from 16 to 6 GPa (and a decrease in the film density by a factor of two) with an increasing CH4 flow was observed. Then, the hardness and Raman results were correlated with the H content in the coatings, showing that these indirect methods can be used to find if there are variations in the H content with the increase in the CH4 flow. Finally, the adhesion and tribological performance of the coatings were evaluated. No significant differences were found in the adhesion as a function of the H content. The tribological properties presented a slight improving trend with the increase in the H content with a decrease in the wear rate and friction.

Simultaneous intercalation of lithium, potassium and strontium into graphite in molten salts medium

The LiCl–KCl molten salts method has been used in order to intercalate strontium into graphite. Combination of X-Ray Diffraction (XRD) experiments and ion beam analyses attests the obtaining of a monophasic sample. Its chemical composition corresponds to the Li0.2K0.6Sr0.4C6 formula, revealing the synthesis of a quaternary Graphite Intercalation Compound (GIC), in agreement with the high repeat distance of 640 pm determined from its 00l XRD and with the 1D electronic density profile. The very high-quality data obtained by hk0 diffraction and rotating crystal method lead to a 2D organization of the intercalated sheet described by a large hexagonal unit cell containing 78 carbon atoms. Such quaternary phase including simultaneously alkali and alkaline-earth metals is unique and can only be prepared from molten salts method, opening new perspectives concerning graphite-based two-dimensional materials.

Decomposition of CrN induced by laser-assisted atom probe tomography

It is known that measurement parameters can significantly influence the elemental composition determined by atom probe tomography (APT). Especially results obtained by laser-assisted APT show a strong effect of the laser pulse energy on the apparent elemental composition. Within this study laser-assisted APT experiments were performed on Cr0.51N0.49 and thermally more stable (Cr0.47Al0.53)0.49N0.51, comparing two different base temperatures (i.e. 15 and 60 K), laser wavelengths (i.e. 532 and 355 nm) and systematically modified laser pulse energies. Absolute chemical compositions from laser-assisted APT were compared to data obtained from ion beam analysis. The deduced elemental composition of CrN exhibited a strong increase of the Cr content when the laser pulse energy was increased for both laser wavelengths. For low laser pulse energies Cr, CrN, N and N2 ions were identified, while the amount of detected Cr ions increased and the amount of N ions strongly decreased at higher laser pulse energies. Further, increased detection of more complex Cr-containing ions such as Cr2N at the expense of CrN was observed at higher pulse energies. At the highest pulse energy levels used within this work, the resulting Cr content was > 80 at%, dominated by the amount of detected elemental Cr ions. The change of the mass spectrum of the detected ions with increasing laser pulse energy provides evidence that high laser pulse energies initiate the decomposition of CrN during the APT measurement, consistent with the known thermal decomposition path into Cr2N and subsequently into Cr and gaseous N. In contrast, variation of the laser pulse energy for the thermally more stable CrAlN resulted only in a slight increase of Cr and a decrease of the resulting concentrations of Al and N with increasing laser pulse energy and no change in the type of detected ions. In conclusion, within the present study, the decomposition of a coating material with low thermal stability induced by laser-assisted APT was reported for the first time, emphasizing the importance of the selection of suitable measurement parameters for metastable materials, which are prone to thermal decomposition.

Elemental characterization of freeze dried domestic animals’ milk using ion beam analysis techniques

Particle induced X-ray emission (PIXE) and particle induced γ-ray emission (PIGE) techniques were employed to perform elemental analysis in four milk samples of local domestic animals, namely sheep, caw, camel and goat. Additionally, Rutherford backscattering (RBS) spectra were acquired simultaneously with PIXE and PIGE to determine matrix elements. Milk samples were prepared in a simple dried base following freeze drying process. Optimization of PIXE/PIGE/RBS experimental conditions as well as data acquisition and analysis procedures were carefully addressed. Verification study was performed relying on the analysis of both IAEA-11 and IAEA-153 reference materials. Accuracies of ±5–10% together with relative standard deviations of less than 15% were mostly reported. Chemical element concentrations of 11 elements were determined, namely Na, Mg, P, S, Cl, K, Ca, Zn, Br, Rb and Sr. Obtained element concentration values were mostly in the range 1000–10000 μg/g for major elements and 5–100 μg/g for trace elements. No significant changes in elemental concentration differences for both trace and major elements were noticed in the four different milk samples. The contribution of the elements in these milk samples to the dietary recommended intakes (DRI) has been evaluated. Advantages of applying multiple ion beam analysis techniques have been discussed.

Silicon oxynitride nanofilms prepared by PLD with controlled Eu-local concentration for broadband white light emitters

We report the successful preparation and characterization of active silicon oxynitride thin films with controlled europium (Eu) doping by alternated pulsed laser deposition. The successful Eu doping with a nanostructured dopant distribution, as well as the stoichiometry of the oxynitride film, have been determined by ion beam analysis (RBS). The oxidation state of the incorporated Eu ions has been determined by in-depth x-ray photoelectron spectroscopy (XPS) and it is shown that the Eu ions are in the 2+ state, in contrast to the usual results found in oxide matrices for which the 3+ oxidation state prevails. The Eu-doped films show an intense broadband emission (FWHM >210 nm) associated to the optical transition 4f65d1 → 8S7/2 of the Eu2+ ions within the amorphous matrix. As expected, the intensity of the emission band increases as the Eu concentration increases, and it is remarkable that the emission shifts towards longer wavelengths. In terms of the chromatic coordinates (CIE) this implies a color tuning from a bluish to orange that enables color tunable emission, and potential white like emission by combining layers with different Eu2+ ions concentration. Therefore, the developed oxynitride films with controlled Eu2+ ions concentration achieved by PLD are promising for the development of color -tailored LED's.

Tuning of the electronic and vibrational properties of epitaxial MoS2 through He-ion beam modification

Atomically thin transition metal dichalcogenides (TMDs), like MoS2 with high carrier mobilities and tunable electron dispersions, are unique active material candidates for next generation opto-electronic devices. Previous studies on ion irradiation show great potential applications when applied to two-dimensional (2D) materials, yet have been limited to micron size exfoliated flakes or smaller. To demonstrate the scalability of this method for industrial applications, we report the application of relatively low power (50 keV) 4He+ ion irradiation towards tuning the optoelectronic properties of an epitaxially grown continuous film of MoS2 at the wafer scale, and demonstrate that precise manipulation of atomistic defects can be achieved in TMD films using ion implanters. The effect of 4He+ ion fluence on the PL and Raman signatures of the irradiated film provides new insights into the type and concentration of defects formed in the MoS2 lattice, which are quantified through ion beam analysis. PL and Raman spectroscopy indicate that point defects are generated without causing disruption to the underlying lattice structure of the 2D films and hence, this technique can prove to be an effective way to achieve defect-mediated control over the opto-electronic properties of MoS2 and other 2D materials.

Fuel retention and carbon deposition on beryllium marker tiles from JET tokamak main chamber limiters investigated by ion beam analysis

The JET tokamak with the ITER-like wall is operated with arrays of castellated beryllium (Be) limiters in the main chamber. In several locations Be marker tiles were installed for erosion-deposition studies. The castellation sides and the plasma-facing surfaces (PFSs) of Be marker tiles from three different locations of the JET main chamber, from the experimental campaigns 2011–12 (ILW-1) and 2013–14 (ILW-2), were analysed, employing 2H and 3He micro-beams in order to determine carbon (C) impurity deposition and deuterium (D) retention. The deposited C and D amounts on the castellation sides (up to 1.5 mm deep into the groove) were assessed with respect to the ion/electron drift direction. Both the C and D amounts on the investigated castellation sides either stay constant or reduce with depth from the edge of the PFS. No systematic difference is observed in the C deposition or D retention on the different castellation sides of each sample with respect to the ion/electron drift direction. C and D content is found to be lower on the PFS than on surfaces in the gaps of castellation for the majority of the samples. The C amount is, in general, higher than the D one. No systematic correlation between the C and the D amounts has been observed.

Hydrogen sorption in yttrium-based getter thin films

We investigated the sorption of hydrogen by yttrium-based getters for their application to vacuum wafer-level packaging of microelectromechanical systems. Thin alloy films were co-evaporated under ultra-high vacuum on silicon wafers. Getters were activated by annealing during 1 h under inert argon atmosphere with traces of oxidizing species, at temperatures ranging from 200 °C to 400 °C. Three complementary techniques of ion beam analysis were performed on the samples: Rutherford Backscattering Spectrometry (RBS), Nuclear Reaction Analysis (NRA) and Elastic Recoil Detection Analysis (ERDA), to quantify metal, oxygen and hydrogen contents, and their in-depth distributions. The results show that oxidation occurs during annealing and prevents or not hydrogen sorption depending on the film composition. Due to its fast diffusion, hydrogen tends to accumulate near the film/substrate interface and starts to diffuse into the substrate as well. The different compositions of getter films are compared in terms of oxygen and hydrogen absorptions.

Bias and synergy in the self-consistent approach of data analysis of ion beam techniques

Using multiple ion beam analysis measurements or techniques combined with self-consistent data processing generally allows for extracting more (or more accurate) information than processing data from single measurements separately. Solving ambiguities, improving the final depth resolution, defining constraints and extending applicability are the main strengths of the data-fusion approach, which essentially consists in formulating a multi-objective minimization problem that can be tackled by the adoption of the weighted-sum method. A simulation study is reported in order to evaluate the systematic error inserted in the analysis by the choice of a specific objective function, or even by the weights or normalization adopted in the weighted-sum method. We demonstrate that the bias of the analysed objective functions asymptotically converges to the true value for better statistics and that the measurement can be ranked by its information content, where some combinations of measurements better constrain the multi-objective optimization.

Carbon erosion/deposition on the divertor of W7-X during the operational period OP 1.2b

Carbon net erosion and deposition at the test divertor unit (TDU) of Wendelstein 7-X (W7-X) were measured for the discharge period OP 1.2b in the year 2018 using 18 specially prepared target elements in all 10 TDUs. These had lengths between 30 and 60 cm and were coated with marker layers for erosion/deposition investigations of 5–10 μm carbon on top of about 300 nm molybdenum. The marker layer thicknesses were measured by elastic backscattering spectrometry (EBS) before and after plasma exposure using 2.5 MeV protons; the surface morphology was investigated using scanning electron microscopy (SEM) and focused ion beam cross-sectioning (FIB), the surface roughness was determined using a two-dimensional optical profiler. Plasma-exposed surfaces were considerably smoother than unexposed surfaces with decreased mean roughness and a shift of the inclination angle distribution towards lower values. The erosion on the 10 TDUs was unequal within a factor of about two. During the discharge period in total 20.4 ± 5.7 g carbon was eroded from the 10 TDUs. Adjacent to the strike line some deposition of carbon was observed. Compared to the discharge period OP 1.2a in the year 2017, the net carbon erosion rate dropped by a factor of 5–6 due to regular boronizations, which reduced the oxygen (and subsequently also the carbon) content in the plasma by 1–2 orders of magnitude. The significance of erosion/deposition processes for long-pulse discharges is discussed.

Study of the Elastic Scattering in the d + 11B system for EBS purposes

The implementation of boron in several fields, such as in the creation of p-type semiconductors in electronics, has created the need for the accurate quantitative determination of its depth profile concentrations in near surface layers of various matrices. In the framework of IBA techniques a combination of Elastic Backscattering Spectroscopy, along with Nuclear Reaction Analysis, has been proposed in order to address the current needs for boron depth profiling, focusing on the use of proton beams. Deuteron beams however offer superior mass resolution with similar stopping power values and simultaneous excitation of most light elements. Unfortunately, the lack of experimental datasets concerning the deuteron elastic scattering on boron impedes their use. Thus, in the present work, the first set of measurements for the 11B(d,d0) differential cross section covering the Ed,lab=1300-1860 keV energy range for the backscattering angles of 150ο, 160ο and 170ο were carried out. The study was conducted at the 5.5 MV Tandem Accelerator of the Institute of Nuclear and Particle Physics, in the National Center of Scientific Research “Demokritos”, Athens, Greece. The target was a thin, self-supporting aluminum foil, upon which a thin natB (isotopic ratio: 11B 80.1%, 10B 19.9%) layer was deposited using the sputtering technique at RBI, Zagreb, Croatia, followed by the evaporation of an ultra-thin layer of 197Au on top for normalization and wear protection purposes. The outgoing particles were detected using silicon surface barrier (S.S.B.) detectors and the differential cross sections for elastic scattering were determined from the resulting spectra via the relative technique

How Particle Deformability Influences the Surfactant Distribution in Colloidal Polymer Films.

The distribution of surfactants in waterborne colloidal polymer films is of significant interest for scientific understanding and defining surface properties in applications including pressure-sensitive adhesives and coatings. Because of negative effects on appearance, wetting, and adhesion, it is desirable to prevent surfactant accumulation at film surfaces. The effect of particle deformation on surfactant migration during film formation was previously investigated by Gromer et al. through simulations, but experimental investigations are lacking. Here, we study deuterium-labeled sodium dodecyl sulfate surfactant in a poly(butyl acrylate) latex model system. The particle deformability was varied via cross-linking of the intraparticle polymer chains by differing extents. The cross-linker concentration varied from 0 to 35 mol % in the copolymer, leading to a transition from viscoelastic to elastic. Ion beam analysis was used to probe the dry films and provide information on the near-surface depth distribution of surfactant. Films of nondeformable particles, containing the highest concentration of cross-linker, show no surfactant accumulation at the top surface. Films from particles partially deformed by capillary action show a distinct surfactant surface layer (ca. 150 nm thick). Films of coalesced particles, containing little or no cross-linker, show a very small amount of surfactant on the surface (ca. 20 nm thick). The observed results are explained by considering the effect of cross-linking on rubber elasticity and applying the viscous particle deformation model by Gromer et al. to elastically deformed particles. We find that partially deformed particles allow surfactant transport to the surface during film formation, whereas there is far less transport when skin formation acts as a barrier. With elastic particles, the surfactant is carried in the water phase as it falls beneath the surface of packed particles. The ability to exert control over surfactant distribution in waterborne colloidal films will aid in the design of new high-performance adhesives and coatings.

Preface

The first joint PIXE and IBA conference was due to take place in Toyama, Japan during October 2021. Unfortunately, due to the global pandemic it was decided to hold this meeting virtually and come back to Toyama in 2023 when, we all hope, travel will become a little easier again. Similarly, the 23rd International Secondary Ion Mass Spectrometry Conference (SIMS23) was due to be held in Minneapolis, USA in September 2021 and was postponed to September 2022.The Ion Beam Analysis (IBA) conference has a long history starting in 1973 in June at the IBM Research Labs in Yorktown Heights, NY, USA. The Particle Induced X-Ray (PIXE) conference also has a long history also dating back to the 1970s (it was then the International Conference on Particle Induced X-ray Emission and its Analytical Applications). It was reconfigured in 2010 and the name shortened to just PIXE. Both conferences are now biennial meetings. The previous PIXE meeting was held in Lisbon, Portugal in March 2019 and the previous IBA meeting was held in Antibes, France in October 2019. The SIMS conference series started in 1977 in Munster, Germany and has run biennially since then until this year. The 22nd meeting took place in Kyoto, Japan.Traditionally the IBA conference deals with the science, development, techniques and applications of energetic ion beams for analysis. This has, over the years, become focused on the application of MeV ion beams, their transport and interaction with surfaces and their application on materials analysis with techniques such as RBS, PIXE, NRA, ERD, IBIC, IBIL and MeV-SIMS. The PIXE conference, on the other hand has often focused on a specific theme for each meeting – the previous meeting’s theme was “Unravelling secrets from atoms to planets” and aimed to emphasize the expanding multi-scale scope of the technique, supported by recent developments. The SIMS conference series provides a forum for the exchange of results and new ideas on Secondary Ion Mass Spectrometry and related techniques.List of Organising committee, Co-chairs of joint conference IBA/PIXE&SIMS, Virtual scientific committee, IBA committee, PIXE committee, SIMS International Committee, SIMS International Scientific Committee are available in this Pdf.

An expert-assisted system for improving the quality of IBA simulations by SIMNRA

SIMNRA is a popular software suite for the simulation of ion beam analysis (IBA) spectra. SIMNRA 7.04 implements a new expert system supporting users in selecting the most accurate simulation settings for a given ion/target combination at a given energy and geometry. The expert system is a piece of artificial intelligence emulating the ability and knowledge of a human IBA expert. It points out potential problems with the current simulation parameters and recommends model settings with enhanced accuracy.

Retention of deuterium in beryllium: A combined investigation using TDS, ERDA and EBS

We have studied the retention of deuterium in beryllium, implanted with an energy of 500 eV/D, using a combination of thermal desorption spectroscopy, elastic recoil detection analysis and elastic backscattering spectroscopy. The parallel use of these techniques allowed us to directly quantify the absolute deuterium content reduction of the sample for specific desorption peaks observed during thermal annealing. In addition, the presence of a beryllium oxide surface layer was observed, despite sputter-cleaning of the sample was initially conducted in-situ . A main result was that ∼ 85 % of the retained deuterium got released during the primary desorption peak at 400 K. A smaller, secondary desorption peak was identified at 540 K. All deuterium could be removed from the Be sample by heating it to a temperature of 800 K. • Deuterium retention in saturated beryllium studied for 500 eV/D irradiation. • Parallel temperature desorption spectroscopy and ion beam analysis achieved in-situ. • 85% of deuterium is released at primary desorption peak at 400 K. • BeO formation during implantation was observed in UHV conditions.

Differential Cross-section Measurements for Deuteron Elastic Scattering on 11B

The implementation of boron in several fields, such as in the creation of p-type semiconductors in electronics, has created the need for the accurate quantitative determination of its depth profile concentrations in near surface layers of various matrices. In the framework of IBA techniques, a combination of Elastic Backscattering Spectroscopy (EBS), along with Nuclear Reaction Analysis (NRA), has been proposed in order to address the current needs for boron depth profiling, based on the use of a proton beam. Deuterons offer superior mass resolution with respect to protons, having similar stopping power values, but, unfortunately, the lack of experimental datasets concerning the deuteron elastic scattering on boron impedes their use. Thus, in the present work, the first set of measurements for the 11B(d,d0) differential cross sections covering the Ed,lab=1300-1860 keV energy range for the backscattering angles of 150°, 160° and 170° was carried out. The study was conducted at the 5.5 MV Tandem Accelerator of the Institute of Nuclear and Particle Physics, in the National Center of Scientific Research “Demokritos”, Athens, Greece. The target was a thin, self-supporting aluminum foil, upon which a thin natB (isotopic ratio: 11B 80.1%, 10B 19.9%) layer was deposited using the sputtering technique at RBI, Zagreb, Croatia, followed by the evaporation of an ultra-thin layer of 197Au on top for wear protection and normalization purposes. The outgoing particles were detected using 6 Silicon Surface Barrier (S.S.B.) detectors and the differential cross sections for the elastic scattering were determined from the resulting spectra via the relative measurement technique.

Possible modifications of parchment during ion beam analysis

Ion beam analysis (IBA) is an established method to determine the concentration and the distribution of elements in art and archaeological objects. However, especially for organic specimens, caution must be taken to avoid harmful effects. In this work, the possible modification of recent calf parchment samples by proton beam irradiation was investigated applying fluences (given as deposited charge per unit area) both within and beyond the usual analytical practice. Attenuated Total Reflection Fourier Transform Infra-red Spectroscopy (FTIR-ATR) and Optical Coherence Tomography (OCT) were employed to assess changes, inspected from the surface of the samples. Although both techniques are apt to detect alterations of parchment in general, in the case of particles, which deposit the majority of their energy below the surface these techniques could not detect changes at low fluences. However, a simple “bath test” (short immersion in liquid) proved that disintegration within the material had already happened. After the “bath test”, OCT and digital 3D microscopy were used to check the discontinuities in the material, especially for low fluences when the visual inspection might have missed them. Unfortunately, simply monitoring organic objects such as parchment during or after ion beam irradiation, non-destructively, is not sufficient to claim absolute harmlessness, as some studies in the past did. In line with our former findings using electron microscopy on cross sections, we found that 2.3 MeV protons with a deposited charge of 0.5 µC/cm2 caused no changes affecting the integrity of parchment but 2 µC/cm2 apparently did under the applied experimental conditions. To ensure the required analytical signal at a relatively low deposited charge, the detection system must be optimized for efficiency. Nevertheless, since the variability of the historic materials and the measurement set-ups are considerable, these values cannot be taken as absolutes, but only as guides, both for further IBA studies and for studies conducted in the past.

Characterising the pigment on a Mesolithic cranium from Corsica using ion beam analysis

Characterising thin mineral layers on heterogeneous media is a significant challenge in archaeometry. Nevertheless, obtaining such geochemical and mineralogical data can, in many cases, provide valuable information about the original raw-material procurement strategies and document the chaîne opératoire leading to the finished object. In this contribution, we report on the geochemical analysis of a thin layer of red mineral pigment found on a skull from the Mesolithic burial of Campu Stefanu, Corsica. A proton ion beam analysis was conducted at the New AGLAE facilities (Palais du Louvre, Paris) to determine major, minor and trace element compositions. Contribution from the pigment’s elemental composition is statistically differentiated from that of the bone and the sediment. Furthermore, the composition of the pigment is shown to be compatible with that of iron-oxide rich mineral blocks found within the mortuary deposits.

Non-vacuum room temperature-processed sintering method of molybdenum pattern by intense pulsed light irradiation for high-performance electronic devices

In this study, the molybdenum (Mo) pattern was realized via intense pulsed light (IPL) irradiation process under ambient condition, without vacuum deposition process. The screen printing method was applied to realize a certain pattern using conductive ink composed of Mo nanoparticles. This printed Mo pattern showed low electrical conductivity due to oxide film on the nanoparticles surface. To improve this drawback, the IPL irradiation process was optimized for sintering of Mo pattern, therefore the remarkable electrical conductivity (35 μΩ·cm) was observed after IPL irradiation process. To investigate the microstructure and other reaction effects of Mo pattern, the various analysis was conducted such as scanning electron microscope, X-ray diffraction, focused ion beam analysis. This printed Mo pattern was applied for the source and drain (S/D) electrode of indium gallium zinc oxide (IGZO) based thin film transistor (bottom gate; TFT). The interfacial microstructure between Mo pattern and IGZO layer was investigated by transmittance electron microscope analysis. Consequently, the TFT with IPL-sintered Mo (S/D) pattern showed a noteworthy saturation mobility of 13.5 cm2·(V·s)−1.