MeV Ion Beam Research Articles

Upgrade of the ion beam analysis end-station with the wavelength dispersive X-ray spectrometer for use with the focused MeV ion beams

A novel modular end-station has been developed for use with focused MeV ion beams. It supports analysis of micro-samples using simultaneously several ion beam analysis (IBA) techniques, including wavelength dispersive (WD) and energy dispersive (ED) Particle Induced X-ray Emission (PIXE) spectrometry, Elastic Backscattering Spectrometry (EBS and RBS) and Nuclear Reaction Analysis (NRA). The end-station enables quantitative elemental analysis, including the creation of two-dimensional elemental maps based on the ED-PIXE and EBS/RBS/NRA measurements. The in-house developed wavelength dispersive X-ray (WDX) spectrometer can measure high energy resolution spectra on selected sample micro-regions. In this work the description of the modular end-station is presented, highlighting the features of the WDX spectrometer: i) in the complementary analysis of complex ED X-ray spectra with many overlapping peaks measured simultaneously and ii) in chemical speciation studies. An example is presented to demonstrate the capabilities of the modular system for simultaneous analytical measurements of selected heterogeneous micro-samples.

Analysis of Rutherford backscattering spectra with CNN-GRU mixture density network

Ion Beam Analysis (IBA) utilizing MeV ion beams provides valuable insights into surface elemental composition across the entire periodic table. While ion beam measurements have advanced towards high throughput for mapping applications, data analysis has lagged behind due to the challenges posed by large volumes of data and multiple detectors providing diverse analytical information. Traditional physics-based fitting algorithms for these spectra can be time-consuming and prone to local minima traps, often taking days or weeks to complete. This study presents an approach employing a Mixture Density Network (MDN) to model the posterior distribution of Elemental Depth Profiles (EDP) from input spectra. Our MDN architecture includes an encoder module (EM), leveraging a Convolutional Neural Network-Gated Recurrent Unit (CNN-GRU), and a Mixture Density Head (MDH) employing a Multi-Layer Perceptron (MLP). Validation across three datasets with varying complexities demonstrates that for simple and intermediate cases, the MDN performs comparably to the conventional automatic fitting method (Autofit). However, for more complex datasets, Autofit still outperforms the MDN. Additionally, our integrated approach, combining MDN with the automatic fit method, significantly enhances accuracy while still reducing computational time, offering a promising avenue for improved analysis in IBA.

Characterization of a HPHT boron ion-implanted diamond X-ray mirror following high vacuum annealing

The incorporation of boron into a diamond lattice holds the potential to advance X-ray optics, offering the capability to manipulate various parameters of the lattice. This includes enhancing near-infrared absorption relative to pure diamond, thereby enabling Q-switchable optics. The use of MeV boron implantation emerges as a promising method for precisely doping the diamond lattice. However, for these optics to function effectively as Bragg-reflecting mirrors, ion implantation must be executed with meticulous attention to maintaining a strain-free, perfect diamond lattice. This study aimed to investigate the feasibility of utilizing a 9 MeV ion beam for high energy boron implantation. Different areas of a high-pressure, high-temperature (HPHT) diamond sample were subjected to irradiation with 9 MeV Boron ions, ranging in fluences from 5×1015 to 2.5×1016ions/cm2. Following boron implantation, high-temperature vacuum annealing was performed to restore the diamond lattice. Our assessment utilized X-ray rocking curve imaging, surface profilometry, and micro-Raman spectroscopy, with additional observations on near-infrared transmission properties. Our measurement of high-quality Bragg reflection through X-ray rocking curve imaging, sensitive to implantation-induced strain and defects, served as an key diagnostic for the effectiveness of this ion-implanted sample as a Bragg-reflecting optic.

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.

Quantitative Lithiation Depth Profiling in Silicon Containing Anodes Investigated by Ion Beam Analysis

The localisation and quantitative analysis of lithium (Li) in battery materials, components, and full cells are scientifically highly relevant, yet challenging tasks. The methodical developments of MeV ion beam analysis (IBA) presented here open up new possibilities for simultaneous elemental quantification and localisation of light and heavy elements in Li and other batteries. It describes the technical prerequisites and limitations of using IBA to analyse and solve current challenges with the example of Li-ion and solid-state battery-related research and development. Here, nuclear reaction analysis and Rutherford backscattering spectrometry can provide spatial resolutions down to 70 nm and 1% accuracy. To demonstrate the new insights to be gained by IBA, SiOx-containing graphite anodes are lithiated to six states-of-charge (SoC) between 0–50%. The quantitative Li depth profiling of the anodes shows a linear increase of the Li concentration with SoC and a match of injected and detected Li-ions. This unambiguously proofs the electrochemical activity of Si. Already at 50% SoC, we derive C/Li = 5.4 (< LiC6) when neglecting Si, proving a relevant uptake of Li by the 8 atom % Si (C/Si ≈ 9) in the anode with Li/Si ≤ 1.8 in this case. Extrapolations to full lithiation show a maximum of Li/Si = 1.04 ± 0.05. The analysis reveals all element concentrations are constant over the anode thickness of 44 µm, except for a ~6-µm-thick separator-side surface layer. Here, the Li and Si concentrations are a factor 1.23 higher compared to the bulk for all SoC, indicating preferential Li binding to SiOx. These insights are so far not accessible with conventional analysis methods and are a first important step towards in-depth knowledge of quantitative Li distributions on the component level and a further application of IBA in the battery community.

Absolute Local Quantification of Li as Function of State-of-Charge in All-Solid-State Li Batteries via 2D MeV Ion-Beam Analysis

Direct observation of the lithiation and de-lithiation in lithium batteries on the component and microstructural scale is still difficult. This work presents recent advances in MeV ion-beam analysis, enabling quantitative contact-free analysis of the spatially-resolved lithium content and state-of-charge (SoC) in all-solid-state lithium batteries via 3 MeV proton-based characteristic x-ray and gamma-ray emission analysis. The analysis is demonstrated on cross-sections of ceramic and polymer all-solid-state cells with LLZO and MEEP/LIBOB solid electrolytes. Different SoC are measured ex-situ and one polymer-based operando cell is charged at 333 K during analysis. The data unambiguously show the migration of lithium upon charging. Quantitative lithium concentrations are obtained by taking the physical and material aspects of the mixed cathodes into account. This quantitative lithium determination as a function of SoC gives insight into irreversible degradation phenomena of all-solid-state batteries during the first cycles and locations of immobile lithium. The determined SoC matches the electrochemical characterization within uncertainties. The presented analysis method thus opens up a completely new access to the state-of-charge of battery cells not depending on electrochemical measurements. Automated beam scanning and data-analysis algorithms enable a 2D quantitative Li and SoC mapping on the µm-scale, not accessible with other methods.

Dynamic Behavior of Li in Solid-State Li-Ion Batteries Studied using MeV Ion Beam Analysis Techniques

In this review, various studies on the Li depth profiles of metal/electrolyte/metal capacitors and batteries of Au/LCO/LATP/Pt, LCO/LiPON/Si, and LMO/LiPON/NbO with different metal electrodes at both sides (by bias; LCO =LiCoO2, LATP =Li3.1Al0.86Ti1.14Ge1.27P1.73O12, LMO =LiMn2O4, NbO = Nb2O5) using the in-situ reflection ERD (ERD) technique with 9MeV O+4 ion beam and transmission ERD (TERD) technique with 5MeV He+2 ion beam, respectively, are described. For capacitors, the transport fraction of Li-ion in the electrolyte is less than unity. The Li atoms diffuse in the direction opposite to the ion. It has been shown that the batteries are rechargeable. On the other hand, it is observed that an anomalous over-charging takes place when the batteries are over-biased (Si/LiPON/LCO and LMO/LiPON/NbO), and strong reactions of Li with the metal electrodes take place under these conditions. The anomaly observed is explained in terms of the imbalance in the capacities of Li in anode and cathode, which can be attributed to the sizeable amounts of hydrogen present as an impurity during the fabrication of the battery. This is because hydrogen can potentially reduce the capacity of Li in both anode and cathode. The reactions of Li with metal electrodes are discussed in terms of the transport fraction of Li ions (less than unity) and the difference in the work functions of metal electrodes at both sides. Finally, it is noted that the removal of hydrogen in batteries can potentially improve safety, efficiency, and lifetime. These can be achieved by reducing the reaction of Li with metal electrodes. The recoil-scatter method in the TERD technique can measure the Li depth profile in the absence of background yields.

A New High-Throughput Focused MeV Ion-Beam Analysis Setup

The analysis of material composition by ion-beam analysis (IBA) is becoming a standard method, similar to electron microscopy. A pool of IBA methods exists, from which the combination of particle-induced-X-ray emission (PIXE), particle induced gamma-ray analysis (PIGE), nuclear-reaction-analysis (NRA), and Rutherford-backscattering-spectrometry (RBS) provides the most complete analysis over the whole periodic table in a single measurement. Yet, for a highly resolved and accurate IBA analysis, a sophisticated technical setup is required integrating the detectors, beam optics, and sample arrangement. A new end-station developed and installed in Forschungszentrum Jülich provides these capabilities in combination with high sample throughput and result accuracy. Mechanical tolerances limit the device accuracy to 3% for RBS. Continuous pumping enables 5 × 10−8 mbar base pressure with vibration amplitudes < 0.1 µm. The beam optics achieves a demagnification of 24–34, suitable for µ-beam analysis. An in-vacuum manipulator enables scanning 50 × 50 mm² sample areas with 10 nm accuracy. The setup features the above-mentioned IBA detectors, enabling a broad range of analysis applications such as the operando analysis of batteries or the post-mortem analysis of plasma-exposed samples with up to 3000 discrete points per day. Custom apertures and energy resolutions down to 11 keV enable separation of Fe and Cr in RBS. This work presents the technical solutions together with the quantification of these challenges and their success in the form of a technical reference.

Energy deposition by nonequilibrium charge states of MeV I127 in Au

The energy loss of iodine ions at initial charge states up to 25+ and energies up to 36 MeV in self-supporting gold foils between 37 and 107 nm of thickness was measured with an electron mirror type time-of-flight detector. An excess energy loss of 130 keV was observed at 36 MeV for charge state 25+ compared to 16+, and an energy loss deficit of 100 keV was observed for charge state 8+. The charge state equilibration length for 36-MeV iodine was estimated to lie between 3 and 7 nm, corresponding to an equilibration time between 0.4 and 0.9 fs. This result is relevant both for nanostructure fabrication with MeV ion beams and for depth profiling based on ion beam analysis data in cases where the charge state of the primary ion is far from the equilibrium value in the sample under study. A comparison to published data on charge state equilibration for various projectile-target combinations and energies from 10 keV to 6 GeV indicated that the energy scaling of the equilibration length observed at high energy is invalid for projectile velocities on the order of the Bohr velocity and below. The measurement further provided equilibrium values of the electronic stopping power for iodine in gold at ten energies between 10 and 36 MeV.

Current status and future developments of the ion beam facility at the centre of micro-analysis of materials in Madrid

We report on the current status of the ion beam laboratory of the Centre of Micro-Analysis of Materials at the Autonomous University of Madrid. The 5 MV accelerator facility provides MeV ion beams of any stable element. Six main beam lines are under operation, allowing the analysis and modification of materials through ion beam methods. Although the most demanded ions are H and He for standard Rutherford backscattering spectrometry and particle-induced X-ray emission experiments, many other analytical techniques and specific set-ups are available for users. The facility especially highlights for the use of high-energy heavy ions and microbeams, with important applications in material science, optics and electronics, biology, cultural heritage, and astrophysics. Ongoing upgrades of the facility are oriented to improve the quality of the service for external users and to face new scientific and technological challenges in areas such as advanced materials, space, energy and health.

Measurement of 12Cq+ and 35Clq+ ion induced X-ray production cross sections in V, Zr and Sn metal oxide films at 0.1 MeV/u - 1.0 MeV/u energies

Experimental X-ray production cross sections in matter are key to fundamental ion-atom interaction studies. They also find practical applications such as in the advancement of ion beam materials analysis techniques like Particle Induced X-ray Emission (PIXE) spectroscopy. Experimental work shows that heavy ion probes induce higher X-ray yields in target atoms compared to light ions of the same velocity. This, in principle, implies higher sensitivity for PIXE analyses performed using heavy ions (Heavy Ion PIXE). There is therefore need for substantial experimental data to improve existing theoretical models that describe X-ray production due to heavy ion-atom collisions. This article presents measurements carried out to determine K-shell X-ray production cross sections in vanadium (V) due to 12Cq+ ions, and L-shell X-ray production cross sections in zirconium (Zr) and tin (Sn) due to 12Cq+ (q = 2, 3) and 35Clq+ (q = 3, 5, 6, 7) MeV ion beams within a velocity range of 0.1 MeV/u - 1.0 MeV/u. Measured cross sections are compared with predictions by the modified Plane Wave Born Approximation (PWBA) and the ECPSSR theory. Observed agreements and discrepancies between experiment and theory are discussed in terms of the underlying ionisation mechanisms.

Photoluminescence enhancement and high accuracy patterning of lead halide perovskite single crystals by MeV ion beam irradiation

Using MeV ion irradiation, a PL enhancement effect of MAPbBr3 single crystals is demonstrated.

Gafchromic HD-V2 investigations using MeV ion beams in vacuum

ABSTRACTGafchromic HD-V2 films are employed to study the response to light ions useful in radiotherapy, such as protons, helium and carbon beams. The effects induced by the ions at an energy within about 300 keV and 16 MeV were investigated in terms of optical absorbance measurements in the irradiated active region of the film. The employed ion doses range between 0.4 Gy and 12 kGy. The results show that the net optical density increases almost exponentially with the absorbed dose and that it becomes saturated after prolonged dose higher than 1 kGy. The optical density produced in the film was measured by light transmission measurements at 700 nm wavelength, at which is observed the highest gafchromic sensitivity. Calibration curves of optical density versus exposure dose and type of ion are given. The dependence on the ion stopping power was presented and discussed.

Li depth profiles of metal/Li-electrolyte/metal capacitors under biasing studied by means of MeV ion beam analysis techniques

Li Depth profiles at the interfaces of capacitors of Cu/LiPON/Cu and Al/LiPON/Al prepared on buffer Ti layer /SiO2glass and Au/LATP/Au (LiPON = Li3.3PO3.8N0.2, LATP = Li3.1Al0.84Ti1.16Ge1.27P1.73O12) under biasing bottom metal against top metal at earth potential have been in-situ measured by means of elastic recoil detection analysis (ERD) and Rutherford backscattering spectrometry (RBS) techniques. Li has been found to be enriched near the interface with electrode biased negatively, while it is depleted near that biased positively. The Li depth profile in electrolyte has been theoretically calculated, taking into account the transport faction of Li ions, based on hopping diffusion model of Li ions under potential gradient. It is shown that the Li depth profile calculated as a solution of diffusion equation at steady state agrees qualitatively well with the experimental ones and the transport fraction of Li ions in electrolyte is less than unity.

Quantal Release of Dopamine and Action Potential Firing Detected in Midbrain Neurons by Multifunctional Diamond-Based Microarrays.

Micro-Graphitic Single Crystal Diamond Multi Electrode Arrays (μG-SCD-MEAs) have so far been used as amperometric sensors to detect catecholamines from chromaffin cells and adrenal gland slices. Besides having time resolution and sensitivity that are comparable with carbon fiber electrodes, that represent the gold standard for amperometry, μG-SCD-MEAs also have the advantages of simultaneous multisite detection, high biocompatibility and implementation of amperometric/potentiometric protocols, aimed at monitoring exocytotic events and neuronal excitability. In order to adapt diamond technology to record neuronal activity, the μG-SCD-MEAs in this work have been interfaced with cultured midbrain neurons to detect electrical activity as well as quantal release of dopamine (DA). μG-SCD-MEAs are based on graphitic sensing electrodes that are embedded into the diamond matrix and are fabricated using MeV ion beam lithography. Two geometries have been adopted, with 4 × 4 and 8 × 8 microelectrodes (20 μm × 3.5 μm exposed area, 200 μm spacing). In the amperometric configuration, the 4 × 4 μG-SCD-MEAs resolved quantal exocytosis from midbrain dopaminergic neurons. KCl-stimulated DA release occurred as amperometric spikes of 15 pA amplitude and 0.5 ms half-width, at a mean frequency of 0.4 Hz. When used as potentiometric multiarrays, the 8 × 8 μG-SCD-MEAs detected the spontaneous firing activity of midbrain neurons. Extracellularly recorded action potentials (APs) had mean amplitude of ∼-50 μV and occurred at a mean firing frequency of 0.7 Hz in 67% of neurons, while the remaining fired at 6.8 Hz. Comparable findings were observed using conventional MEAs (0.9 and 6.4 Hz, respectively). To test the reliability of potentiometric recordings with μG-SCD-MEAs, the D2-autoreceptor modulation of firing was investigated by applying levodopa (L-DOPA, 20 μM), and comparing μG-SCD-MEAs, conventional MEAs and current-clamp recordings. In all cases, L-DOPA reduced the spontaneous spiking activity in most neurons by 70%, while the D2-antagonist sulpiride reversed this effect. Cell firing inhibition was generally associated with increased APs amplitude. A minority of neurons was either insensitive to, or potentiated by L-DOPA, suggesting that AP recordings originate from different midbrain neuronal subpopulations and reveal different modulatory pathways. Our data demonstrate, for the first time, that μG-SCD-MEAs are multi-functional biosensors suitable to resolve real-time DA release and AP firing in in vitro neuronal networks.

Inlet MeV ion beam dependence of transmission property for a glass capillary filled with He gas

To obtain an intense ion beam extracted into air, the glass capillary optics filled with He gas were developed and the intensity distribution of an ion beam via this capillary measured at high and low inlet current conditions was investigated. It was found that the intensity of the ion beam via this capillary hardly changed when increasing the He gas pressure in the high inlet current condition, whereas an enhancement of the intensity was observed in the low inlet current condition, even considering the relative uncertainty of the inlet current. The degree of enhancement of the ion beam depends on not only the straggling in the atmospheric gas, but also on the ion beam current, because of the space charge.

Using high energy electrons for Elastic Recoil Detection of hydrogen

Materials that incorporate hydrogen are of great interest for both scientific and technological reasons. The Ion Beam Laboratory at Sandia National Laboratories has developed techniques using micron to mm-size MeV ion beams to recoil H and its isotopes (Elastic Recoil Detection or ERD) that can very accurately make such measurements. However, there are many measurements that would benefit the field of materials science and technology that require much better resolution. To address these and many other issues, we have demonstrated that H can be recoiled through a thin film of Mylar by 70 keV electrons and detected with a channeltron electron multiplier (CEM). The electrons were steered away from the CEM by strong permanent magnets. This has proven the feasibility that the high energy electrons from a Transmission Electron Microscope-TEM can potentially be used to recoil and subsequently detect (e-ERD), quantify and map the concentration of H isotopes with nm resolution.

Development of an ion beam induced luminescence set-up with a temperature controlled target stage and its application

To explore the irradiation damage and the ion beam induced luminescence (IBIL) during ion implantation at various temperatures, a MeV ion beam induced luminescence measuring set-up with a temperature controlled target stage (attainable temperature range from 77 K to 873 k) has been established at the GIC4117 Tandem accelerator in Beijing Normal University. On the IBIL spectra of lithium fluoride (LiF) at various temperatures under the 2 MeV H+ irradiation, the significant influences of temperature on luminescence were observed. Several mechanisms influenced by temperature could be the cause of different evolution behaviors under different temperatures, such as the vacancy migration rate, annealing effect and non-radiative recombination. The ‘‘double-exponential’’ model was employed to get the value of the half-brightness radiation fluence F1/2, to get the information about the sensitivity of photon yield to the irradiation damage and recovery.

Implementation of a multilayer model for measurement of thermal conductivity in ion beam irradiated samples using a modulated thermoreflectance approach

Laser based modulated thermoreflectance (MTR) technique is an attractive method for measuring thermal conductivity in ion irradiated samples. Unlike laser flash analysis, traditionally used for measuring thermal conductivity in nuclear materials, the MTR method is sensitive to damage that is only a few micrometers thick. This allows MTR to detect damage resulting from a few MeV ion beam irradiation. MTR combined with tailored ion beam irradiations offers a promising opportunity for validation of lower-scale thermal conductivity models developed for irradiated materials. In this technique, a harmonically modulated laser pump heats the irradiated sample and a probe beam measures the temperature induced changes in the sample's reflectivity. Interpretation of the measured temperature profiles in ion irradiated samples is complicated by the nonhomogeneous damage profile and the presence of an additional thin metal transducer layer. In this work, we present a detailed analysis of the experimentally measured thermal wave profiles in UO2 samples irradiated with 2.6 MeV H+ ions using different multilayer approximations of the damaged region. The limitation of an infinite damage layer approximation that assumes uniform damage across the thickness of the sample and neglects the undamaged region is discussed. Presented analysis outlines the method for determination of the applicability range for the infinite damage model. Finally, an analysis of the impact of point defects on thermal transport in irradiated samples is presented as an example for implementation of the MTR approach for validation of thermal transport models.

Simultaneous microbeam IBA and beam-induced luminescence analysis of strained doped silica fibre radiation dosimeters

We demonstrate that the simultaneous combination of ion beam analysis (IBA) and ion beam induced luminescence (IL) can reveal valuable information concerning the performance of strained doped silica fibre thermoluminescence microdosimeters. The micron scale spatial resolution and low detection limits of IBA allow the lateral distribution of dopant elements to be mapped and then correlated with the distribution of prompt radioluminescence. Measurement of the decay of the IL signal with dose provide information concerning the saturation of the subsequent TL signal at high doses. MeV ion beams can deposit relatively high energy in localized, well-quantified small volumes and so this method is valuable for studying high dose effects in TL dosimeters. We describe a simple modification of the target chamber microscope which enables sensitive low background light detection in two wavelength bands and present preliminary results from three types of germanium doped silica fibre dosimeter.