Surface analysis techniques such as tandem (MS/MS) time-of-flight mass spectrometry and X-ray photoelectron spectroscopy (XPS) are used to identify and understand the distribution and mode of binding of corrosion inhibitors on the metal surface. A corrosion inhibitor is a chemical compound added in a very small amount to a corrosion medium. When a metallic material is immersed in a corrosive medium, the corrosion inhibitor mitigates corrosion by adsorbing onto the metal surface. A gas cluster ion beam (GCIB) sputtering source is a very suitable technique for analyzing thin organic coatings without chemically altering their composition. In this work, the surface layer of a self-assembled corrosion inhibitor on a metal surface was analyzed. The conformation was determined using MS/MS ToF-SIMS, a rare technique in the SIMS database. GCIB sputtering and 3D ToF-SIMS imaging were used for 3D distribution analysis. The analysis showed that the chloride was located under the surface layer of the corrosion inhibitor. This finding was confirmed by GCIB-XPS analysis using Ar cluster beam sputtering at different acceleration energies and cluster sizes.

To enable the use of a high-capacity Li-metal anode in All-Solid-State-Batteries (ASSBs), the stability of the Solid-Electrolyte (SE) against Li-metal is crucial for the development of next generation batteries. Besides commonly used characterization techniques such as X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS), secondary ion mass spectrometry (SIMS) presents itself with its high sensitivity, lateral resolution and 3D elemental mapping as a valuable tool for deconvoluting the characteristics of the buried Li/SE interface. The reactivity of Li-metal imposes additional challenges for the experimental setup, which calls for the development of advanced analytical techniques.¹

First established by Wenzel et al.², in-situ deposition of Li-metal onto the SE via sputtering of a Li-metal target, followed by XPS analysis, elucidates the stability of the Li/SE interface upon contact. A similar approach was later used within a SIMS instrument: Otto et al.³ investigated the stability and microstructure of the interface between Li metal and different inorganic SEs. The development of a designated preparation chamber with an attached effusion cell enabled the in-situ deposition of Li-metal onto the SE.

Following a similar setup to Otto et al.³, this study extends the in-situ characterization of the Li/SE-interface to Solid Polymer Electrolytes (SPEs). Compared to their rigid inorganic counterparts, flexible SPEs maintain better contact to the electrode, which reduces dendrite growth and contact resistance.⁴ While the employment of SPEs in ASSBs is widely studied, the elusive Li/SPE-Interface is yet to be characterized.

Herein, we present an in-situ TOF-SIMS study of said interface to shed light on its microstructure, stability, and chemical composition. Using a newly developed preparation chamber, Li-metal is in-situ deposited onto SPEs and the forming interface is analyzed. Comparing other Li-deposition methods, evaluating the evolution of the interface over time, and characterizing its composition, yields a systematic investigation of the stability of the Li/SPE-interface.

Using MgO as a reference substrate, we establish a reliable routine to deposit Li-metal with a low temperature effusion cell. Li-deposition on SPEs and subsequent depth-profiling reveals differences in stability and chemical composition of the Li/SPE-interface. To unveil the relevant signals within the various polymer fragments, the data are evaluated via statistical methods such as principal component analysis (PCA).

This presentation outlines the first application of our new designated preparation chamber for the in-situ deposition of Li-metal on SPEs and summarizes the experimental set-up, which ultimately enabled us to characterize the Li/SPE-Interface.

References

1. Banerjee, A., Wang, X., Fang, C., Wu, E. A. & Meng, Y. S. Interfaces and Interphases in All-Solid-State Batteries with Inorganic Solid Electrolytes. Chemical Reviews 120, 6878–6933; 10.1021/acs.chemrev.0c00101 (2020).

2. Wenzel, S. et al. Direct Observation of the Interfacial Instability of the Fast Ionic Conductor Li 10 GeP 2 S 12 at the Lithium Metal Anode. Chem. Mater. 28, 2400–2407; 10.1021/acs.chemmater.6b00610 (2016).

3. Otto, S.-K. et al. In Situ Investigation of Lithium Metal–Solid Electrolyte Anode Interfaces with ToF‐SIMS. Adv Materials Inter 9, 2102387; 10.1002/admi.202102387 (2022).

4. Ding, P. et al. Polymer electrolytes and interfaces in solid-state lithium metal batteries. Materials Today 51, 449–474; 10.1016/j.mattod.2021.08.005 (2021).

The application of low and high energy ion beam techniques has played a pivotal role in Lebanon for over a decade, enabling the identification of fraudulent practices employed in Lebanese currency, as well as essential products like food and pharmaceutical drugs.

In this study, we present an innovative approach utilizing the Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) technique to address specific inquiries posed by the counterfeiting combating section of the central bank of Lebanon. The primary objectives were to determine the types of materials employed in the production of counterfeit 1k and 5k Lebanese Lira (L.L.) secure stripes, the printing processes involved in counterfeiting the highest denomination, 100k L.L., and the identification of the UV ink used in the forgery of this banknote. Based on the 3D analysis with the Ar source, our analysis revealed compelling evidence suggesting that the counterfeit stripes found on the 1k and 5k L.L. banknotes were most likely made from aluminum gift papers. Furthermore, our investigation demonstrated that the individuals behind the counterfeiting operation possessed a deep understanding of the genuine banknote production process, as the layer printing technique employed in the fake 100k L.L. banknotes closely mirrored that of the authentic ones. Regarding the identification of the UV ink used in the counterfeiting process, our findings indicated that the ink utilized in the fake 100k L.L. banknotes was a commercially online available variant.

The outcomes of this investigation unveil the counterfeit techniques employed and contribute to enhancing law enforcement's ability to combat financial fraud and safeguard the integrity of Lebanese currency.

Introduction:

The organic matter contained in primitive meteorites called chondrites, is a witness to the early stages of formation of the Solar System. Better characterizing it and understanding the way it interacted with mineral phases and the extent, to which it evolved under secondary processes within the parent asteroid, are critical issues in astrochemistry. In this work, we present the study of two differently aqueously altered CM chondrites, Cold Bokkeveld [1] and Paris [2,3], together with an ordinary LL5 chondrite, Tuxtuac [4] used as a control sample. The aim of this study is to understand the effect of parent body hydrothermal processes on the organic matter structure, composition and localization within the mineral matrix. Thus, all the samples were analyzed without any chemical extraction by TOF-SIMS [5] with a specific focus on comparing and localizing organic signatures.

Materials and methods:

Freshly cut millimetric fragments of the three meteorites were analyzed using a TOF-SIMS V spectrometer. Areas of 500µm*500µm were analyzed using 30keV Bi₃⁺ clusters emitted from a LMIG nanoprobe (0.3pA) and focused to 5µm, diameter spot. Cleaning with argon clusters was performed systematically prior to the analyses according to an established previous protocol [5]. We also analyzed in the same conditions a set of “CHO” and “CHON” films produced in laboratory, in order to help for the interpretation of the macromolecular signatures.

Results and discussion:

The organic matter contained in these primitive samples is composed of very complex mixtures of a large diversity of molecules and macromolecules randomly structured and highly cross-linked [6,7]. At masses lower than 150u, the three meteorites have undistinguishable organic matter average signatures. At higher masses, while organic matter signatures exhibit large and multiple peaks at each mass unit that corroborate their very complex and random structure, the characteristic signatures differ slightly from one sample to another and seem to indicate that the hydrothermal process tend to increase the oxygen content and the unsaturation degree of the organic matter. This latter increase would be consistent with a previous study that found an increase of the aromaticity degree with aqueous alteration [8].

Another finding that will be discussed is related to organo-iron and organo-silicon features. Both were found in the samples and confirm a previous result on the Paris meteorite [5], whereas no organo-magnesium nor any other organo-alkali feature was found. This result emphasizes the particularly strong interaction that must be present between the chondrite silicates and especially the iron-rich phyllosilicates, and the organic matter. Finally, we will discuss the localization of alkalis in both CMs and their relation to salts, organic salts included.

[1]Rubin A. et al. (2007)Geochimica et Cosmochimica, A71(9), 2364-2382

[2]Hewins R.H. et al. (2014)Geochimica et Cosmochimica, A124, 190-222

[3]Marrochi Y. et al. (2014)Meteoritics&Planet. Sci., 49(7), 1232-1249

[4]Graham A. L et al. (1988)Meteoritics, 23: 321

[5]Noun M. et al. (2019 Life, 9(2), 44

[6]Alexander C.M.O.D. et al. (2017)Chemie der Erde/Geochemistry, 77 227

[7]Botta, O. & Bada, J. L. (2002)Surveys in Geophysics, 23, 411

[8]Alexander C.M.O.D. et al. (2014)Meteoritics&Planet. Sci., 49(4), 503-52

The alkali-silica-reaction (ASR) and the resulting damage mechanism are a major problem for the durability of concrete, causing millions of dollars of damage annually. Affected are structures that come into contact with water and thus a large part of the global infrastructure such as roads, runways, bridges and railroad sleepers. The cause of a damaging ASR is the swelling alkali silica gel, which results from the reaction of alkali ions of the pore solution with reactive silicates from the aggregate. While numerous factors such as the influence of moisture, temperature, alkali content of concrete, and the role of admixtures have been intensively investigated, important questions regarding the role of specific dissolved ions in the pore solution are still unresolved. In this context, aluminum ions are of particular interest due to their potential to prevent a deleterious ASR.

The overall goal of this research project is to understand the influence of an aluminum containing passivating layer on the ASR reaction and its damage mechanism in detail. The focus lies on the characterization of the surface layer formation in dependence of various parameters, for example the silicate surface it forms on, temperature, time, and the concentration of aluminum in the solutions.

Depth profiling time-of-flight secondary ion mass spectrometry (ToF SIMS) and X-ray photon spectroscopy (XPS) investigations were carried out on different silicate samples (e.g. quartz glass) that had been stored in sodium hydroxide solutions in the presence or absence of aluminum ions. These comparative studies revealed that alumina was enriched in the near-surface region. Moreover, slightly higher values were detected for the photoelectron binding energy of aluminum than expected for Al₂O₃, indicating very small nanoparticles and/or the formation of an aluminosilicate (Published under DOI: 10.1002/sia.6918).

Further work is dedicated to a transfer the knowledge gathered with model compounds to different silicate rocks prone to ASR reactions. Here, the influence of foreign ions from the minerals is expected to alter the reaction mechanism.

Macro-autophagy, hereafter referred to as autophagy, is an evolutionary conversed degradation process that removes unnecessary and dysfunctional cytosolic components through the lysosome pathway. In this way, autophagy guards against metabolic fluctuations by supplying cells with amino acids during periods of stress, and maintains cytoplasmic function by removing old and dysfunctional proteins and organelles. Dysregulation of autophagy has been linked to the progression of pathologies, most notably neurodegenerative diseases where the decrease of autophagy activity leads to the accumulation of toxic proteins. This protein accumulation reflects the disturbed cellular proteome. Rapamycin, a drug known as an autophagy inducer via the mTOR pathway, has been shown to convey positive effects on diseases in both cell and animal models. However, the underlying molecular mechanism of autophagy towards pathologies and the rescuing effects of rapamycin have not been fully understood. The combination of NanoSIMS and confocal fluorescence microscopy provides a powerful tool to investigate these molecular connections at a subcellular level.

This project aims to study the molecular relation between autophagosome activity and protein turnover in human neuronal progenitor cells (NPC), obtained from both healthy and Schinzel–Giedion Syndrome (SGS) neurodegenerative patients. This holds great potential in understanding the fundamental role of autophagy in neurodegenerative diseases and developing effective therapies.

Methods. To determine the autophagosome turnover rate, the fusion between autophagosome and lysosome is inhibited using Chloroquine, and then the rate at which autophagosomes accumulate in the cells is determined as a measure of autophagosome turnover. For correlative confocal and NanoSIMS imaging, cells are loaded with ¹⁵N-Leucine for two days followed by a clearing period in regular cell medium. Afterwards, autophagosomes are labelled with fluorescent markers, and the cells are embedded in LR white resin, cut into thin sections, and imaged using confocal microscopy followed by NanoSIMS. These two images will be overlaid using cellular structures that are easily recognized, such as the nucleus and cell borders, allowing locating of individual autophagosomes and their respective protein turnover. In addition, mitochondria are used as a reference for organelle turnover.

Results. Healthy NPC exhibited higher autophagosome turnover and cytosolic/mitochondrial protein turnover compared to SGS highlighting a difference in the dynamic molecular events between healthy and diseased cells, and a possible involvement of autophagy in disease burden. No differences in protein turnover in the nucleus of healthy and SGS cells were observed, owning to autophagy's cytosolic-selective degradation. In addition, ¹⁵N enrichment within the autophagosomes was similar to that in the cytosol regardless of treatment in both cell types. Finally, rapamycin did not affect SGS cytosolic/mitochondria protein turnover, however, the healthy cells showed an unexpected increase in ¹⁵N enrichment despite enhanced autophagosome turnover which may be due to the underlying molecular mechanism of Leucine.

Dye-sensitized solar cells (DSSCs) offer creative design possibilities in terms of shape, color and transparency, and perform relatively better at diffuse light conditions when compared to other solar cell technologies. These differentiating properties make DSSCs an interesting candidate for niche creative applications and building integrated photovoltaics. Recently, DSSCs have been used to introduce the concept of so-called photovoltaic photographs, solar cells wherein images are captured by controlled light-induced patterning, or selective bleaching, of the light-absorbing molecules [1]. The proposed method allows direct integration of high-resolution patterns, such as images, logo's and text, into the photoactive layer of the solar cell, thereby circumventing common issues with traditional patterning methods such as scalability, ease of fabrication, and transferability.

In this study, we examine the underlying light-induced degradation mechanism occurring in ruthenium dye N719, a commonly used dye for high-performance DSSCs, using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) (TOF.SIMS 5 NCS, IONTOF GmbH, Germany. Device located at imec, Leuven - Belgium). A comparison of the mass spectra obtained at bleached and non-bleached areas of the photoanode provides insight into the degradation mechanism. Principle component analysis (PCA) is used to accelerate the identification of discriminating secondary ions. The results suggest that the observed N719 degradation involves a photo-induced oxidation mechanism of the thiocyanate ligands bound to the central ruthenium atom. The results are discussed and an outlook on future work is provided.

[1] J. Hustings et al., Sol. Energy Mater Sol. Cells 246 (2022)

Beams of cluster particles of various sizes and stoichiometric compositions are currently widely used both in SIMS and in numerous other applications of ion technologies [1]. Among the cluster generation methods, ion sputtering [2] has a number of advantages; however, the nature of cluster formation processes during ion bombardment is still largely unclear. The main analytical models of cluster formation under the action of ion bombardment cannot, as a rule, describe the experimental mass distributions of sputtered clusters, which for homogeneous particles, depending on the number of atoms n in them, are described by the power law Y(n)~n^-δ [2], where δ=4÷9 and depends on the sputtering coefficient. Using synergetic concepts, it was shown in [3] that by analysis of the sputtering process by a set of “reactions” of the type where А are surface atoms, X are sputtered atoms, and n and m are integers, one can obtain the distribution the probability of the number of atoms P_S(n) in sputtered cluster, and when the equilibria of these reactions are shifted, P_S(n) has a non-Poisson character in accordance with experiments [1].

To determine the possibility of describing the processes of cluster formation during ion sputtering in the framework of [3], taking into account the combinatorial nature of these processes [4], we performed extensive SIMS studies of the emission and fragmentation in all stoichiometrically possible directions of Si_n⁺, Si_nO_m^±, V_nO_m^± and Nb_nO_m^±± clusters. The experiments were carried out according to a technique similar one used in [5], when Si, V, and Nb targets were sputtered by Xe⁺ beams and O₂ was inletted onto bombarded surfaces.

The volume performed by SIMS studies of the processes of emission and decay of clusters shows that, both for homogeneousr and heterogeneous clusters, the process of their formation under ion sputtering of surfaces can be described in frameworks of synergistic concepts [3]. The combinatorial approach [4] in this case can serve as an effective method for the analysis of quasi-chemical reactions in which certain clusters of a specific size and stoichiometric composition are formed.

[1] Popok V.N., Barke I., Campbell E.E.B., Meiwes-Broer K.-H. //Surf. Sci. Reports. 2011. V.66. P.347-377. https://doi.org/10.1016/j.surfrep.2011.05.002

[2] Wucher A. Sputtering: Experiment. //Matematisk-fysiske Meddelelser. Det Kongelige Danske Videnskabernes Selskab. Copenhagen, 2006. V.52. P.405-432.

[3] Maksimov S.E., Oksengendler B.L., Turaev N.Yu. // Journal of Surface Investigation. 2013. V.7. №2. P.333–338. https://doi.org/10.1134/S1027451013020407

[4] Dzhemilev N.Kh. //Journal of Surface Investigation. 2012. V.6. №4. P.254–258. DOI:10.1134/S1027451012080083

[5] Dzhemilev N.Kh., Kovalenko S.F., et al. //Journal of Surface Investigation. 2017. V.11. № 3. P.490–495. DOI: 10.1134/S1027451017010074

Polyurea thickened greases have gained increasing interest particularly in the lubrication of electric motor bearings, due to its inherent oxidative stability and high operating temperature. However, they can be difficult to manufacture due to the health and safety concerns of the starting materials (isocyanates). Additionally, fully understanding the grease structure is crucial in comprehending and improving the final grease properties. Previous attempts at defining the structure of a grease have largely been via scanning electron microscopy (SEM). However, removal of the base oil component is required prior to analysis, which modifies the true structure. Here, we develop a method for in depth chemical and structural analysis of polyurea grease using a similar protocol employed in the cryo-OrbiSIMS analysis of frozen hydrated biofilms [1]. Emphasis is placed on characterising the grease without distorting the original microstructure, via high pressure freezing, cryogenic SEM (cryo-SEM) and cryogenic orbital trapping secondary ion mass spectrometry (cryo-OrbiSIMS).

Commercially sourced base polyurea grease was investigated, with the potential to extend into the analysis of polyurea grease synthesised via less hazardous chemistries. The results show that the commercial base grease is amenable to high pressure freezing and analysis via cryo-SEM and cryo-OrbiSIMS. Spherical urea particle like structures distributed in the base oil matrix were observed in the cryo-SEM images. This is in agreement with the cryo-OrbiSIMS imaging, where similar shaped distributions of ions corresponding to urea were observed. Such findings provide important insight into understanding the urea particle shape and size required for optimal performance, and to build a methodology for understanding the structure of materials made from safer chemistries.

[1] Zhang, J.; Brown, J.; Scurr, D. J.; Bullen, A.; Maclellan-Gibson, K.; Williams, P.; Alexander, M. R.; Hardie, K. R.; Gilmore, I. S.; Rakowska, P. D. Cryo-OrbiSIMS for 3D Molecular Imaging of a Bacterial Biofilm in Its Native State. Anal. Chem. 2020, 92, 9008– 9015, DOI: 10.1021/acs.analchem.0c01125

Neuronal progenitor cells (NPCs) give rise to glial and neuronal cell types in the brain during human development as well as acting as a reserve in adulthood. Many extra-and intracellular factors are involved in maintaining the NPCs' function and differentiation, and dysregulated composition of lipids in the plasma membrane is therefore connected to altered brain function and morphology, leading to diseases. The altered lipid composition can also reflect disturbances intracellularly. Despite lipids in the plasma membrane being a useful reflection of cellular health and function, they are commonly overlooked in research. A complicating factor is that the conventional bulk analysis methods for studying the plasma membrane lipids often ignore the molecular differences at the single cell level, or other methods lack the ability to explore the native plasma membrane lipid composition specifically. We aimed to characterize the lipids at the NPC plasma membrane using ToF-SIMS imaging, which overcomes these two limitations. We first explored the native NPC plasma membrane followed by studying the lipid turnover of NPCs using different isotopically labelled lipid precursors, including 13C-choline, 13C-linoleic, 13C-stearic, and 13C-lauric acids. Our results indicate that the NPC plasma membrane contains a high abundance of ceramides, phosphatidic acids, phosphatidylcholines, and glycerophosphoserines. Furthermore, different lipid precursors were found incorporated into different molecular membrane lipids, especially comparing between short- and long-carbon chain fatty acid precursors, and between unsaturated and saturated precursors. The current study illustrates the potential of ToF-SIMS to study neuronal lipids providing molecular- and spatial-rich information in single cells.

Batteries are very important to achieve carbon net zero. Understanding battery materials change, electrode surfaces, solid electrolyte interphase (SEI) evolution and novel solid-state electrolyte structures is very helpful for developing better batteries. Surface chemical analysis techniques such as X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy are often used but they have their limitations. XPS analysis cannot always resolve overlapping binding energies for some key SEI elements. The SEI often has poor Raman signal intensity. These are all hurdles for battery applications.

Secondary ion mass spectrometry has great potential to study interfacial chemistry in batteries owing to high sensitivity and high-resolution imaging in 2D and 3D. In this study, we use an OrbiSIMS instrument which is equipped with two complementary mass spectrometers (MS). A time-of-flight (ToF) MS has the capability for 2D and 3D imaging using a Bi₃⁺ liquid metal ion gun with a spatial resolution of up to 200 nm but with modest mass resolving power. The Orbitrap MS offers high mass resolution and mass accuracy (> 240,000 at m/z 200 and < 2 ppm, respectively). The instrument is equipped with low energy Cs and O₂ sputter beams for high resolution depth profiling of inorganic materials. It also has a Leica docking station enabling samples to be transferred using a vacuum sample transfer chamber from an argon glove box without atmospheric exposure. To improve the quality of measurements on battery materials, we have used ion implanted materials to determine relative sensitivity factors for relevant elements. We have also conducted a systematic study to optimise the OrbiSIMS depth profiling capability. These findings along with recommendations to reduce effects of signal saturation will be discussed and examples of the application to batteries will be provided. We will provide examples of the application of ToF MS and Orbitrap MS. (1,2)

1. X. Yao et al., Energy Environ. Sci., 2023, DOI: 10.1039/D2EE04006A.
2. S. Marchesini et al., ACS Appl. Mater. Interfaces, 14(2022)52779-52793.

In order for most biological specimens to be analyzed with ToF-SIMS, either the water must be removed via a process such as freeze-drying or the samples must be frozen and analyzed under cryogenic conditions. Cryogenic preparation and analysis of biological samples preserves the 3-dimensional structure of tissues and biofilms and can prevent migration artifacts that occur during freeze-drying. However, ToF-SIMS analysis of water ice results in a spectrum of ice cluster ions extending to high masses that can interfere with detection of biomolecules. Furthermore, metastable decay of the ice cluster ions in the time-of-flight analyzer can lead to a high background that raises the detection limit for target analytes. In this study, we have investigated the influence of a range of analytical parameters, including primary ion species and cluster size, analysis temperature and time-of-flight analyzer settings on the water ice spectrum. The aim of this work is to optimize analysis conditions in order to improve the detection limit for antibiotic compounds.

Three antibiotic compounds, ciprofloxacin, tetracycline and rifampicin, have been investigated. Each of the three antibiotics was prepared at a concentration of 1 mg/ml in an aqueous solution containing 5% dextran and 150 millimolar ammonium formate. The aqueous solutions were pipetted onto a thin copper mold in a dry argon atmosphere. The copper mold with the solution was then plunge-frozen in liquid propane, cooled further in liquid nitrogen on a copper block and then transferred (without exposure to moist air) into an IONTOF M6 equivalent instrument, which is equipped with an active liquid nitrogen heating/cooling system in both the load-lock and the analysis chamber. Six different primary ion species were studied. These included 30 keV Bi₁⁺, Bi₃⁺ and Bi₅⁺ and 2 keV Ar₁₀₀₀⁺, Ar₁₅₀₀⁺ and Ar₂₀₀₀⁺. In between analysis scans, a GCIB sputter scan (2 kV, 2 nA, Ar₂₀₀₀⁺) was used to create a fresh surface. Measurements were performed in two different analyzer modes, with and without extraction delays. The analysis temperature was varied from -175 °C to -90 °C.

Details of the spectral changes resulting from analysis temperature, primary ion species and size and analyzer settings will be presented. For each of the analysis conditions, the ratio of the antibiotic molecular ion to ice cluster ions was evaluated. A gradual increase in this ratio was observed with increasing temperature until rapid freeze-drying of the sample is observed near -90 °C. Additionally, the ratio of antibiotic molecular ion to water ice ions decreased with increasing bismuth cluster size, but for increasing argon cluster sizes the opposite trend was observed. Using delayed extraction led to an additional increase in the ratio of antibiotic to water ice ions. Based on these results, recommendations for optimal analysis conditions for detection of the antibiotics will be presented.

Electrocatalysis is and will continue to play a central role in the development of a new and modern sustainable economy, especially for chemicals and fuels. The storage of excess electrical energy into chemical energy by splitting water into hydrogen and oxygen is a feasible solution in this economic sector. A major drawback of electrical energy lies in the storage. Therefore, hydrogen is discussed as promising alternative. Fortunately, this issue can be effectively addressed through the implementation of chemical storage mechanisms. Due to their abundance on Earth and inherent stability in alkaline solutions, transition-metal oxides have become one of several viable alternatives to conventional noble-metal catalysts. Since FeNi oxide is one of the most active oxygen evolution reaction (OER) electrocatalysts for alkaline water electrolysis, it has been the subject of extensive research.

A series of different types of FeNi oxide nanoparticles (NPs) with atomic ratios covering a broad range, and various sizes with specific stoichiometric and non-stoichiometric iron and nickel ratios was synthesized and characterized by the combination of surface analysis techniques, such as time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The morphology was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which revealed the coexistence of mixed and unmixed iron and nickel NPs with comparable sizes in the range of 30–40 nm across all ratios. The synthesis technique displayed control over the iron-nickel ratio, as evidenced by energy dispersive X-ray spectroscopy (EDS) data. The presence of magnetite (Fe₃O₄) was detected in all samples investigated by X-ray diffraction (XRD). Furthermore, the existence of nickel ferrite (NiFe₂O₄) was shown in the Fe₂Ni by XRD analysis. For the cyclic voltammetry (CV) measurements, the NPs were deposited onto glassy carbon electrodes using Nafion^® as an ionomer, and 1 M KOH was employed as the electrolyte. Subsequently, the NPs/Nafion^® electrode was transferred into the ToF-SIMS chamber to allow surface analysis and depth profiling.

The ToF-SIMS analysis revealed distinct peaks corresponding to Fe, Ni, and other peaks associated with Nafion^®, whereas a straightforward correlation between the Ni.Fe ratio and the SIMS peak pattern is not possible.

The catalytic activity towards OER was evaluated through CV measurements, where the Fe₂Ni₃ ratio exhibited the most favorable performance, displaying a lower overpotential.

In the last decade the continuous increase of electric power demand has shifted the attention towards wide band semiconductors (WBG), such as gallium nitride (GaN) and related alloys. An interesting aspect related to GaN materials is the possibility to grow AlGaN/GaN heterostructures with the formation of two-dimensional electron gas (2DEG) and which allows to design AlGaN/GaN high electron mobility transistors (HEMT) structure. A major challenge with this device technology is its normally-ON nature which limits their applications. To improve system reliability, normally OFF HEMTs are highly desirable. One method to achieve this goal is to grow a p-type cap layer (pGaN). The most used acceptor is Mg, having a relatively large ionization energy that has been estimated to be in the range 0.12–0.16 eV, depending on the doping level.[1] Mg-doped GaN is grown by metalorganic vapor deposition - MOCVD with metalorganics and organic compounds and hydrides as precursors (ammonia NH₃,Trimethylgallium - TMGa and biscyclopentadienyl-magnesium - Cp₂Mg), and the growth usually is in H₂ ambient. The consequence is the presence of Mg-H and atomic H which dramatically increases the resistance of Mg-doped GaN [2]. Upon implantation, Mg impurities have to be activated and this is obtained by thermal annealing which induces hydrogen dissociation from the Mg–H complex in the Mg-doped GaN layers. Despite the mechanism is known, there have been only a few quantitative experimental investigations on the relationship between the amount of hydrogen dissociated from Mg-doped GaN and the electronic properties of the p-GaN.

The aim of this study is to correlate the role of hydrogen in the thermal activation process of Mg-doped GaN and the resistivity variation of p-GaN as a function of the temperature up to 800°C. ToF-SIMS was used to evaluate the Mg and H depth profiles [3]. Hall measurements were adopted to investigate the conductive properties of the annealed samples. The sample analyzed are stacks with 100 nm of pGaN, a thin AlGaN layer (around 20nm), grown on GaN buffer layer. H quantification by ToF SIMS on typical GaN/AlGaN structures is tricky since hydrogen is present as a spurious element in the tool main chamber residual atmosphere and walls. Instrumental setting and acquisition mode require particular care in their determination. Further, the H background signal detected by ToF-SIMS is strongly dependent on the matrix, i.e., the analyzed layer composition, thus it is particularly difficult to determine the ultimate H detection limit for the pGaN material. By working on acquisition protocols, we optimized the detection limit and correlated the concentration value obtained with GaN and electronic properties. In particular, Hall measurements show that sheet resistance values are not strictly correlated with H content.

[1] Nardo et al (2022) J. Phys. D: Appl. Phys. 55 185104

[2] S. J. Pearton, A. Y. Polyakov (2010) Chem. Vap. Deposition, 16: 266-274

[3] Y. Nakagawa et al. (2004), Japanese Journal of Applied Physics, 43(1R) 23

Most funding organisations in Europe, USA, and increasingly worldwide, require that data from projects they support be published in an open manner. The acknowledged best practice for this is to follow the ‘FAIR Guiding Principles for scientific data management and stewardship’ [1]. These principles lay out recommendations for both the way data should be presented, and also the metadata relating to the experiments or studies that produced those data. The FAIR Principles define four interlinked categories, by which data should be Findable, Accessible, Interoperable and Reusable.

Related to this, Sir Tim Berners-Lee, the inventor of the Worldwide Web, has defined a 5-star Open Data Plan for data sharing [2]. These stars represent the degree to which data can be accessed and reused by others, with the top rating of five stars being linked open data that is available to all, and ‘machine actionable’. Machine actionability means that our data is presented in such a way that a computer can interpret its meaning and optionally direct a suitable workflow.

In the SIMS community we may share our data, but it is not easily accessible or reusable by those outside our immediate circle. This not only prevents our data being reused by others in their own research, but also inhibits the development of third-party data analysis packages which could grow the technique in unforeseen directions.

Here we present FAIRSpectra, a community-directed project to improve the data sharing practice in the field of SIMS. This activity will:

• Develop a common vocabulary so we can communicate with clearer understanding.
• Deliver this common vocabulary in a standards compliant format.
• Develop a file structure in an open standard file format.
• Produce tools to read and write these data and metadata formats in a range of computer languages.
• Generate training materials to enable the best use of these outcomes.

Benefits of FAIRSpectra will include:

• Ease of integration of our data with existing statistical and machine learning software.
• Better storage and accessibility of our data, in both private and public data stores.
• Greater compliance with funder expectations, potentially leading to more funding.

We invite all interested users to visit FAIRSpectra at https://fairspectra.net to engage in this process and help shape the future of data sharing in SIMS.

[1] Sci Data 3, 160018 (2016). https://doi.org/10.1038/sdata.2016.18

[2] https://5stardata.info/

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is one of the most important techniques for chemical imaging of nanomaterials and biological samples with high lateral resolution. However, low ionization efficiency limits detection of many molecules at low concentrations or in very small volumes.

Matrix-Enhanced SIMS (ME-SIMS), in which an organic matrix is added to the sample, is one promising approach to enhancing ion yield for biomolecules. Optimizing this approach has, however, been challenging because the processes involved in increasing the ion yield in ME-SIMS are not yet fully understood.

To better understand the roles of proton donation and reduced fragmentation on lipid molecule ion yield, ME-SIMS has been combined with cluster primary ion analysis. A DPPC/matrix model system as well as mouse brain cryo-sections which were vapor coated with matrix have been studied. The influence of primary ion species and cluster size have been investigated. Additionally, matrices that vary in acidity have been studied.

The studies reveal that multiple mechanisms are important for enhancing the yield of large molecular ions. Strong evidence that reduced fragmentation of the analyte is a major mode of action of ME-SIMS was observed in both the model system as well as the mouse brain tissue samples. Proton donation from the matrix to the analyte was found to be significant and increased with more acidic matrixes. In addition to these mechanisms, incorporation of the analyte in the matrix and surface segregation of the analyte were shown to play important roles.

These investigations contribute an important advance in the understanding of the mechanisms involved in molecular ion yield enhancement in ME-SIMS. This work demonstrates that cinnamic acid derivative matrices can provide a dramatically softer desorption environment for lipid analysis. In fact, with matrix, Bi₁⁺ primary ions generated nearly an order-of-magnitude greater molecular ion to fragment ion ratio than could be obtained using large Ar gas cluster primary ions without the matrix. This demonstrates a strong potential for improved molecular analysis along with the advantages of the nanoscale focus of the Bi LMIG.

One of the most important thin-film solar cell materials is Cu(In,Ga)Se₂ (CIGS). It reaches a maximum conversion efficiency of 23.6%[1]. Flexible and lightweight solar modules are possible[2]. Traditionally, in a standard stack the CdS buffer forms the pn-junction together with the CIGS absorber. However, due to optical losses in the short wavelength region and in order to improve the ecological foot print of the CIGS solar cell, there are efforts to replace CdS with the more transparent material Zn(S,O)[3].

The band alignment between Zn(S,O) and CIGS depends on the [Ga]/([Ga]+[In]) (GGI) ratio in the absorber material as well as on the sulfur content of the buffer layer. It strongly affects the transport of charge carriers generated by the absorption of light, which in turn is a limiting factor in power conversion. Thus, the [S]/([S]+[O]) ratio (SSO) in the Zn(S,O) buffer plays an important role for optimizing the solar cell performance. Usually, for quantification of the sulfur concentration in Zn(S,O), layers are deposited on a glass substrate and the SSO ratio is estimated from their bang gap as determined by optical transmission measurements. However, the identified SSO ratio in bare layers mostly deviates from the expected theoretical value in the stack, which corresponds to the realized solar cell performance. This raises the question, if the SSO ratio in Zn(S,O) is changed during device processing.

Here we investigate the layer stack ZnO:Al/(Zn,Mg)O/Zn(S,O)/CIGS with ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectroscopy), encompassing the front contact, buffer layers, and absorber layer of the solar cell. The determination of SSO in a complete ZnO:Al/(Zn,Mg)O/Zn(S,O)/CIGS layer stack is a challenge, since the first three layers all contain the elements Zn and O. How can we distinguish between the oxygen in Zn(S,O) from that in (Zn,Mg)O (ZMO)? In our work, we show a way to separate the information from ToF-SIMS data and to quantify it. The SSO differences between Zn(S,O) deposited by sputtering and by chemical deposition can clearly be seen.

[1] https://www.nrel.gov/pv/interactive-cell-efficiency.html

[2] T. Feurer et. al.; Progress in thin film CIGS photovoltaics – Research and development, manufacturing, and applications Progress in Photovoltaics Volume 25, Issue 7, July 2017, p. 645-667; DOI: 10.1002/pip.2811

[3] Xiaowei Jin et. al.; Chemical phases in the solution-grown Zn(O,S) buffer of post-annealed Cu(In,Ga)Se2 solar cells investigated by transmission electron microscopy and electroreflectance; Journal of Applied Physics 133, 165303 (2023) DOI 10.1063/5.0139264

An OrbiSIMS (Hybrid SIMS, IONTOF, Germany) is a dual analyser instrument combining a Time-of-Flight (ToF) mass spectrometer (MS) and an Orbitrap^TM MS, which confer advantages of speed and high-performance mass spectrometry, respectively [1]. There are now several instruments in operation around the world and metrology is needed to help ensure repeatability and reproducibility of the intensity scale. In 2021, we conducted a systematic study of two key parameters in the transfer optics on the transmitted secondary ion intensities [2]. Recently, we have conducted a systematic study of the noise characteristics of the Orbitrap using OrbiSIMS instruments at NPL and at IONTOF [3]. The VAMAS TWA 2 A37 MS interlaboratory comparison aims to build on the methods previously published and study reproducibility of OrbiSIMS experiments for organic and inorganic materials.

Measurement of the Orbitrap^TM noise distribution requires a source of ions that is stable over the time frame of the measurements. The protocol includes simple measurement of a reference silver sample across a range of ion intensities, beam currents and how to measure stability of the primary ion beam current at the sample (typically <1% RSD over a 10-minutes period). The protocol also allows the linearity of the intensity scale to be established.

The Orbitrap^TM requires the ions to have a potential of approximately 50 V and lower kinetic energy distribution than results from the SIMS collision process. Consequently, the sample is biased by a sample target voltage, V_T, necessary to match the acceptance window of the Orbitrap and a bespoke transfer system using an ion guide with helium gas at a pressure, P, which slows the ions and reduces their kinetic energy distribution through elastic collisions with gas atoms. The data acquired using the protocol will be used to map secondary ion intensity in function of V_T and P, as we reported previously. [2].

The protocol will be discussed and participation in the study is encouraged. Samples and protocol will be sent to participants by the end of 2023 and data should be reported by April 2024.

[1] M. K. Passarelli et al., “The 3D OrbiSIMS—label-free metabolic imaging with subcellular lateral resolution and high mass-resolving power,” Nat. Methods, no. november, p. nmeth.4504, 2017, doi: 10.1038/nmeth.4504.

[2] L. Matjacic et al., “OrbiSIMS metrology part I: Optimisation of the target potential and collision cell pressure,” Surf. Interface Anal., no. November 2021, pp. 1–10, 2021, doi: 10.1002/sia.7058.

[3] M. R. Keenan et al., “In preparation.”

Cellulose is the most abundant organic polymer found in nature and it has been historically exploited for many technological applications. Microcrystalline cellulose (MCM) is a purified, partially depolymerized by-product of fibrous plant cellulose that has already regulated and authorized applications as food additive. Nano-sized cellulose fibres can then be extracted from their micro-counterparts. Nanocellulose (NC) is an emerging advanced nanomaterial with several potential applications in the fields of medicine, energy, food and consumer products. NC can be classified in three types according to its source material: (1) nanofibrillated cellulose (NFC), (2) nanocrystalline cellulose (NCC), and (3) bacterial NC (BNC). Several technological pathways exists for the production of NC, exploiting the different biological sources, which in turn affect many physicochemical properties and ultimately the NC surface chemistry. Understanding the variability in the characteristics of different NC materials is crucial for reliable development of NC-based products and their safety assessment.
Increased attention towards NC use in food applications requires a thorough risk assessment that lays its foundation on a careful evaluation of NC material physicochemical properties. Investigating physicochemical properties of NC materials under the conditions applied for in-vitro testing is a prerequisite for proper hazard assessment and for understanding the underlying biochemical mechanisms occurring during NC interactions with living cells and tissues. Therefore we realized a detailed dataset of the physicochemical properties for each different type of NC material, including a microcrystalline cellulose material reference, using a set of orthogonal nano-analytical techniques. The objective was the realization of an interpretative framework for the subsequent toxicity experiments. The study involved Time-of-Flight Secondary Ions Mass Spectroscopy (ToF-SIMS) for the analysis of macromolecular chemistry, x-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) for the characterization of the functional groups chemistry, X-ray diffraction analyses (XRD) for characterization of the crystalline structure and transmission electron microscopy (TEM) for morphological characterization.
The NC materials were ranked in order of decreasing crystallinity, as measured by XRD, where BNC exhibited the highest and NFC “TEMPO-oxidized” the lowest crystallinity value. Functional groups chemistry analysis via XPS and FTIR showed the appearance of COO- functionalities in the NFC Tempo (i.e. catalytic oxidation) samples that are absent in other formulations. The appearance of these residual groups can be attributed to the interaction of NC hydroxyl functionalities and the catalyst oxygen radical. The resulting disruption of the hydrogen bonds network between the NC chains can be further correlated to the loss of crystalline organization observed via XRD. Chemical structure analysis using ToF-SIMS data, processed via multivariate approach (principal component analysis, PCA,) is able to separate the samples based on a first component describing the glucose monosaccharide structure and a second component describing oxidized groups. Samples grouping obtained via PCA reflects individual properties differences measured independently with orthogonal techniques.
NANOCELLUP project has received funding from the European Union through an EFSA grant (GA GP/EFSA/SCER/2020/04). This communication reflects only the author’s view and EFSA is not responsible for any use that may be made of the information it contains.

Introduction

Silicon carbide (SiC) and diamond are wide bandgap semiconductors that have begun to emerge with the development of high-power electronic devices. They have outstanding physical and chemical properties, and are therefore promising materials in several fields of applications: light emitters, high temperature and high-power electronics, high-power microwave devices, micro-electromechanical system (MEMS) technology, substrates...

Offering extreme sensitivity, high depth and lateral resolution together with high throughput, dynamic SIMS (Secondary Ion Mass Spectrometry) proves extremely useful for studying SiC and diamond materials.

Instrumentation

The CAMECA IMS 7f-Auto is a magnetic sector mass analyzer dedicated to dynamic SIMS measurements. It offers depth profiling with excellent detection limits (ppb to ppm) for both dopants and contaminants (H, C, N, O). It also provides unique sub-μm resolution 2D and 3D imaging capabilities, as well as high throughput and automation.

Different applications covered by the CAMECA IMS 7f-Auto related to the development of SiC and diamond materials will be presented.

SiC

Despite the rapid evolution of the SiC technology in recent years, the SiC growth process still faces significant challenges that limit device performance. Optimized doping and reduced impurity incorporation are essential for improving the performance and reliability of SiC devices.

Analytical conditions and data obtained in SiC samples using the CAMECA IMS 7f-Auto will be presented.

Diamond

Many studies focus on the nature and the impact of impurities in diamond thin films synthetized by chemical vapor deposition (CVD). Nitrogen (¹⁴N) is a well-known impurity in synthetic diamonds; it influences growth phenomena, and it is a compensator for acceptor states. It needs to be accurately controlled and measured using dynamic SIMS.

Data obtained on the IMS 7f-Auto on diamond-based structures will be presented.

Conclusions

As for Si technology development for integrated circuits, dynamic SIMS technique is a key tool for R&D of novel materials, as it provides the in-depth distribution of trace elements (dopants and contaminants) with excellent detection limits and high throughput. In addition to depth resolution, dynamic SIMS also offers high lateral resolution that can be used to investigate the non-uniformity of trace elements.

Whilst the success of mRNA-based vaccine in protecting against SARS-CoV-2 infection, there is still much to learn about the role of lipid nanoparticles (LNP) in initiating an immune response. This project aspires to gain some insight into the metabolic impact of LNP’s using state of the art characterisation techniques such as mass spectrometry imaging.

Lipid nanoparticles are delivery vehicles that have unique components that are not endogenously present in cells. These components will be used to follow the delivery vehicle and provide a chemical “fingerprint” for the nanoparticle when using characterization techniques such as secondary ion mass spectrometry (SIMS), specifically 3D-OrbiSIMS. Conventional metabolomic techniques including liquid chromatography mass spectrometry (LC-MS) generally required extensive sample preparation and does not provide any 3D imaging or distribution information for specific chemical compounds.

This work will build on previous work to improve our capacity to interrogate the physiological environments by mapping the chemical fingerprint of the delivery vehicle and metabolic impact of exogenous vaccine mechanisms over time with LNP’s delivered to in-situ cell models and utilising 3D-OrbiSIMS to analyse the metabolomic impact of the LNP’s on the cells over time with hopes to provide key mechanistic evidence to improve the design of vaccine and delivery vehicles by providing insight regarding how delivery occurs and influences the cellular environment ^[1].

[1] Suvannapruk, W. et al. Single-Cell Metabolic Profiling of Macrophages Using 3D OrbiSIMS: Correlations with Phenotype. Anal Chem (2022)

CMOS image sensors, which are mostly used in consumer electronic devices, represent a low cost alternative for the acquisition of high-resolution X-ray and neutron radiographic images with application in biology, electronic component inspection and paleontology. Nevertheless, in order to model the response of the sensor, it is required to know its architecture defined by the composition, size and distribution of the different regions. In that regard, TOF-SIMS has been widely used for characterizing semiconductor devices although the selection of optimal analysis conditions is not trivial at all.

In this work, we present the characterization by TOF-SIMS of a commercial off-the-shelf CMOS image sensor intended to be used as an X-ray detector for acquiring radiographic images of wood specimens. The analyzed sensor is covered with an array of organic microlenses which poses a challenge for the TOF-SIMS analysis. Different analysis conditions (i.e. primary ion species, sputter species and gas flooding) were used for optimizing the detection of the secondary ions of interest, while different strategies (i.e. imaging of cross-sections, depth-profiling from top-surface, and removal of organic lenses) were used for dealing with topographic effects. The performed analysis allow us to detect the presence of a borophosphosilicate glass (BPSG) layer which was crucial for improving the modeling of the CMOS image sensor response and explaining the experimental X-ray image data acquired with the sensor.