TY - JOUR A1 - Chan, George C.-Y. A1 - Engelhard, Carsten A1 - Wiley, Joshua S. A1 - Shoulds, Ayanna U. A1 - Cooks, R. Graham A1 - Hieftje, Gary M. A1 - Shelley, Jacob T. T1 - Characterization of a Low-Temperature Plasma (LTP) Ambient Ionization Source Using Temporally Resolved Monochromatic Imaging Spectrometry N2 - The low-temperature plasma (LTP) probe is a common plasma-based source used for ambient desorption–ionization mass spectrometry (MS). While the LTP probe has been characterized in detail with MS, relatively few studies have used optical spectroscopy. In this paper, two-dimensional (2D) imaging at selected wavelengths is used to visualize important species in the LTP plasma jet. First, 2D steady-state images of the LTP plume for N2+ (391.2 nm), He I (706.5 nm), and N2 (337.1 nm) emissions were recorded under selected plasma conditions. Second, time-resolved 2D emission maps of radiative species in the LTP plasma jet were recorded through the use of a 200 ns detection gate and varying gate delays with respect to the LTP trigger pulse. Emission from He I, N2+, and N2 in the plasma jet region was found to show a transient behavior (often referred to as plasma bullets) lasting only a few microseconds. The N2+ and He I maps were highly correlated in spatial and temporal structure. Further, emission from N2 showed two maxima in time, one before and one after the maximum emission for N2+ and He I, due to an initial electronic excitation wave and ion–electron recombination, respectively. Third, the interaction of the LTP probe with a sample substrate and an electrically grounded metallic needle was studied. Emission from a fluorophore on the sample substrate showed an initial photon-induced excitation from plasma-generated photons followed by electronic excitation by other plasma species. The presence of a grounded needle near the plasma jet significantly extended the plasma jet lifetime and also generated a long-lived corona discharge on the needle. The effect of LTP operating parameters on emission spectra was correlated with mass-spectral results including reagent-ion signals. Lastly, five movies provide a side-by-side comparison of the temporal behavior of emitting species and insights into the interactions of the emission clouds with a sample surface as well as an external needle. Temporally and spatially resolved imaging provided insights into important processes in the LTP plasma jet, which will help improve analyte ion sampling in LTP–MS. KW - Optical spectroscopy KW - Low-temperature plasma KW - Ambient ionization KW - Instrumentation PY - 2023 DO - https://doi.org/10.1177/00037028231184501 VL - 77 IS - 8 SP - 940 EP - 956 PB - SAGE Publications AN - OPUS4-61269 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gauglitz, Günter A1 - Bodensteiner, Michael A1 - Bohleber, Pascal A1 - Clases, David A1 - Dahms, Marcel A1 - Engelhard, Carsten A1 - Haider, Markus A1 - Hayen, Heiko A1 - Herbst‐Irmer, Regine A1 - Jäger, Martin A1 - Kramell, Annemarie E. A1 - Legner, Robin A1 - Matysik, Frank‐Michael A1 - Pöthig, Alexander A1 - Rädle, Matthias A1 - Seifert, Stephan A1 - Steinhauser, Georg A1 - Wolter, Kathrin T1 - Trendbericht Analytische Chemie 2024 N2 - Mehrdimensionale Trenntechniken sowie Kopplungstechniken verbessern weiter die Auflösung in der Analytik. In der Elementanalytik beeindrucken neue Entwicklungen der Massenspektrometrie mit induktiv gekoppeltem Plasma, in der Archäometrie zerstörungsfreie In‐situ‐Analysen. Der 3‐D‐Druck treibt die elektroanalytische Forschung voran, und die Prozessanalytik setzt auf Lab‐on‐a‐Chip und vermeldet Neues bei der Raman‐Spektroskopie mit Flüssigkernlichtleitern. KW - Analytische Chemie KW - Trenntechniken KW - Elementanalytik KW - Massenspektrometrie KW - Prozessanalytik PY - 2024 DO - https://doi.org/10.1002/nadc.20244139242 SN - 1868-0054 VL - 72 IS - 4 SP - 52 EP - 64 PB - Wiley CY - Weinheim AN - OPUS4-62155 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schardt, Annika A1 - Schmitt, Johannes A1 - Engelhard, Carsten T1 - Single particle inductively coupled plasma mass spectrometry with nanosecond time resolution N2 - In this proof-of-principle study, we present our contribution to single particle inductively coupled plasma mass spectrometry (spICP-MS) developments with a novel in-house built data acquisition system with nanosecond time resolution (nanoDAQ) and a matching data processing approach. The new system can continuously sample the secondary electron multiplier (SEM) detector signal and enables the detection of gold nanoparticles (AuNP) as small as 7.5 nm with the commercial single quadrupole ICP-MS instrument used in this study. Recording of the SEM signal by the nanoDAQ is performed with a dwell time of approximately 4 ns. A tailored method was developed to process this type of transient data, which is based on determining the temporal distance between detector events that is denoted as event gap (EG). We found that the inverse logarithm of EG is proportional to the particle size and that the number of detector events corresponding to a particle signal distribution can be used to calibrate and determine the particle number concentration (PNC) of a nanoparticle dispersion. Due to the high data acquisition frequency, a statistically significant number of data points can be obtained in 60 s or less and the main time limitation for analyses is merely the sample uptake time and rinsing step between analyte solutions. At this stage, the data processing method provides average information on complete data sets only and will be adapted to enable particle-by-particle analysis with future hardware/software revision. KW - ICP-MS KW - Nanoparticles KW - Nanosecond time resolution KW - Single particle detection PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612706 DO - https://doi.org/10.1039/d3ja00373f SN - 1364-5544 SN - 0267-9477 VL - 39 IS - 2 SP - 389 EP - 400 PB - Royal Society of Chemistry (RSC) CY - Cambridge AN - OPUS4-61270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schardt, Annika A1 - Schmitt, Johannes A1 - Engelhard, Carsten T1 - Cover image for the article "Single particle inductively coupled plasma mass spectrometry with nanosecond time resolution" N2 - Image for the front cover of the issue 39(2) of the JAAS (Journal of Analytical Atomic Spectrometry). See Annika Schardt et al., pp. 389–400. Image reproduced by permission of Annika Schardt, Johannes Schmitt and Carsten Engelhard. KW - Analytical chemistry KW - Nanoparticles KW - Single-particle characterization KW - Instrumentation KW - spICP-MS PY - 2024 DO - https://doi.org/10.1039/D4JA90005G SN - 1364-5544 SN - 0267-9477 VL - 39 IS - 2 SP - 295 PB - Royal Society of Chemistry (RSC) CY - Cambridge AN - OPUS4-62156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shahsanaei, Majid A1 - Farahbakhsh, Nastaran A1 - Pour-Ali, Sadegh A1 - Schardt, Annika A1 - Orangpour, Setareh A1 - Engelhard, Carsten A1 - Mohajernia, Shiva A1 - Killian, Manuela S. A1 - Hejazi, Sina T1 - Synergistic enhancement of photocatalytic hydrogen production in TiO2 nanosheets through light-induced defect formation and Pt single atoms N2 - In this investigation, we present a direct method employing UV-light radiation to induce point defects, specifically Ti3+ and VO, onto the surface of TiO2 nanosheets (TiO2-NSs) and efficiently decorate them with Pt particles. The addition of the Pt precursor is carried out during rest periods following UV-light cessation (light-induced samples, LI) and during UV-light exposure (photo-deposited samples, PD). The size and distribution of Pt particles on both LI and PD TiO2-NSs are systematically correlated with varying resting times, enabling precise control over Pt loading. The characterization of various TiO2-NSs is extensively conducted using microscopy techniques (FESEM, TEM, and HAADF-STEM) and spectroscopy (XPS). Gas chromatography is also employed for the evaluation of the H2 photocatalytic performance of various samples. Our findings reveal that Pt particles deposit on the TiO2-NSs surfaces as nanoparticles under illumination. After a 5 minutes resting time, a combination of Pt single atoms (SAs) and clusters, with a maximum loading of 0.37 at%, is formed. Extending the resting time to 60 minutes results in a gradual reduction in Pt SAs and clusters, leading to the deposition of Pt nanoparticles with lower loadings. Notably, Pt SAs and clusters exhibit superior performance in hydrogen evolution, showcasing a remarkable 4000-fold increase over pristine TiO2-NSs. Additionally, sustained UV radiation during Pt addition in the photo-deposited samples results in the formation of Pt nanoparticles with lower loading compared to LI samples, consequently diminishing photocatalytic hydrogen production. This study not only provides insights into the controlled manipulation of Pt SAs on TiO2-NSs but also highlights their exceptional efficacy in hydrogen evolution, offering valuable contributions to the design of efficient photocatalytic systems for sustainable hydrogen generation. KW - Chemistry KW - Nanosheets KW - Hydrogen PY - 2024 DO - https://doi.org/10.1039/D4TA01809E VL - 12 IS - 29 SP - 18554 EP - 18562 PB - Royal Society of Chemistry (RSC) AN - OPUS4-61271 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vermeeren, Sarah A1 - Witzler, Markus A1 - Makarow, Ramona A1 - Engelhard, Carsten A1 - Kaul, Peter T1 - Multivariate evaluation method for the detection of pest infestations on plants via VOC analysis using gas chromatography mass spectrometry N2 - Volatile organic compounds (VOCs) play an important role in the defense against pest infestations on plants. The analysis of these VOCs using gas chromatography mass spectrometry (GC-MS) enables the detection of pests by analyzing the VOC composition (VOC profiles) for specific patterns and markers. The analysis of such complex datasets with high biovariability poses a particular challenge. For this reason, a multivariate evaluation method based on a self-written Python script, using principal component analysis (PCA) and linear discriminant analysis (LDA), was developed and tested for functionality using a dataset, which has been evaluated manually and has identified five specific markers (2,4-dimethyl-1-heptene, 3-carene, alpha-longipinene, cyclosativene, and copaene) for Anoplophora glabripennis (ALB) infestation on Acer trees. The results obtained in the present study did not only match the manually evaluated results, but lead to further insight into the dataset. Another sesquiterpene which is assumed to be alpha-zingiberene was identified as an ALB specific marker in addition to 2,4-dimethyl-1-heptene and 3-carene. Furthermore, the European native beetle species goat moth Cossus cossus (CC) and poplar long-horned beetle Saperda carcharias (SC) were also analyzed for their VOCs to differentiate ALB specific VOC from other pest infestations. This comparison lead to the conclusion that the compounds alpha-longipinene, cyclosativene, and copaene are not specific for ALB but for pest infestation in general. It was possible to identify not only specifically produced VOCs, but also differences in concentrations that arise specifically during ALB infestation. Therefore, the evaluation method for the detection of plant pests presented in this study represents a time-saving alternative to conventional non computing methods, which in addition provides more detailed results. KW - Mass Spectrometry KW - Gas Chromatography KW - Volatile organic compounds KW - Pest infestation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639526 DO - https://doi.org/10.1038/s41598-025-11607-5 SN - 2045-2322 VL - 15 IS - 1 SP - 1 EP - 10 PB - Springer Science and Business Media LLC AN - OPUS4-63952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Braun, Jennifer A1 - Engelhard, Carsten A1 - Kaul, Peter T1 - Optimized fast gas chromatography coupled with proton-transfer-reaction time-of-flight mass spectrometry for the selective near real-time analysis of herbivore-induced plant volatiles N2 - The analysis of herbivore-induced plant volatiles (HIPVs) is essential for understanding plant-environment interactions and defense strategies against herbivores. Proton transfer reaction time-of-flight mass spectrometry (PTR–TOF–MS) is a powerful analytical tool that enables real-time monitoring and quantification of diverse groups of HIPVs. However, the PTR–TOF–MS technique is constrained in its ability to effectively differentiate between isomers. When analyzing complex mixtures of HIPVs, the separation of isomers becomes crucial as major compound classes such as terpenes comprise thousands of isomers. In this study, we present an optimized fast gas chromatography (fastGC) based on a modified version of the commercially available fastGC add-on integrated into a mobile PTR–TOF. The system was optimized for the analysis of emissions from enclosed trunks of Acer platanoides infested by Anoplophora glabripennis (Motschulsky), commonly known as Asian longhorned beetle (ALB). The development of fastGC was primarily focused on the sesquiterpenes α-longipinene, cyclosativene and α-copaene, which serve as strong indicators of ALB infestation. These sesquiterpenes were separated in less than three minutes, with intra-day retention time RSD < 0.6 % and resolutions of 2.6 ± 0.3 and 1.3 ± 0.2. In comparison to the original system, the optimized fastGC demonstrates more than tripled sesquiterpene resolution, twice the sensitivity relative to direct inlet mode, and an approximately 10 % reduction in total analysis time. The optimized fastGC–PTR–TOF allows for near real-time analysis of complex mixtures of biogenic VOCs, making it a powerful tool for environmental monitoring, integrated pest management, and forest protection. KW - Mass Spectrometry KW - PTR-TOF-MS KW - Gas Chromatography KW - Herbivore-induced plant volatiles KW - Sesquiterpenes PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639513 DO - https://doi.org/10.1016/j.chroma.2025.466236 SN - 0021-9673 VL - 1759 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-63951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chen, Xinyue A1 - Dong, Ximan A1 - Zhang, Chuyan A1 - Zhu, Meng A1 - Ahmed, Essraa A1 - Krishnamurthy, Giridharan A1 - Rouzbahani, Rozita A1 - Pobedinskas, Paulius A1 - Gauquelin, Nicolas A1 - Jannis, Daen A1 - Kaur, Kawaljit A1 - Hafez, Aly Mohamed Elsayed A1 - Thiel, Felix A1 - Bornemann, Rainer A1 - Engelhard, Carsten A1 - Schönherr, Holger A1 - Verbeeck, Johan A1 - Haenen, Ken A1 - Jiang, Xin A1 - Yang, Nianjun T1 - Interlayer Affected Diamond Electrochemistry N2 - Diamond electrochemistry is primarily influenced by quantities of sp3‐carbon, surface terminations, and crystalline structure. In this work, a new dimension is introduced by investigating the effect of using substrate‐interlayers for diamond growth. Boron and nitrogen co‐doped nanocrystalline diamond (BNDD) films are grown on Si substrate without and with Ti and Ta as interlayers, named BNDD/Si, BNDD/Ti/Si, and BNDD/Ta/Ti/Si, respectively. After detailed characterization using microscopies, spectroscopies, electrochemical techniques, and density functional theory simulations, the relationship of composition, interfacial structure, charge transport, and electrochemical properties of the interface between diamond and metal is investigated. The BNDD/Ta/Ti/Si electrodes exhibit faster electron transfer processes than the other two diamond electrodes. The interlayer thus determines the intrinsic activity and reaction kinetics. The reduction in their barrier widths can be attributed to the formation of TaC, which facilitates carrier tunneling, and simultaneously increases the concentration of electrically active defects. As a case study, the BNDD/Ta/Ti/Si electrode is further employed to assemble a redox‐electrolyte‐based supercapacitor device with enhanced performance. In summary, the study not only sheds light on the intricate relationship between interlayer composition, charge transfer, and electrochemical performance but also demonstrates the potential of tailored interlayer design to unlock new capabilities in diamond‐based electrochemical devices. KW - Nanocrystalline diamond KW - Interfaces KW - Electrochemistry KW - TOF-SIMS KW - SEM PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621576 DO - https://doi.org/10.1002/smtd.202301774 SN - 2366-9608 VL - 9 IS - 2 SP - 1 EP - 10 PB - Wiley VHC-Verlag CY - Weinheim AN - OPUS4-62157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelhard, Carsten T1 - On ICP-MS with Nanosecond Time Resolution: From Nanoparticles to Microplastics N2 - In this presentation, recent developments in inductively coupled plasma mass spectrometry (ICP-MS) instrumentation for particle characterization in complex mixtures will be reviewed. The current state-of-the-art in single-particle (sp) ICP-MS instrumentation for the detection and characterization of nanoparticles (NP) and microplastics (MPs) as well as remaining challenges will be discussed. While millisecond dwell times were used in the advent of spICP-MS, the use of microsecond dwell times helped to improve nanoparticle data quality and particle size detection limits. We could show that a custom-built high-speed data acquisition unit with microsecond time resolution (μsDAQ) can be used to successfully address issues of split-particle events and particle coincidence, to study the temporal profile of individual ion clouds, and to extend the linear dynamic range by compensating for dead time related count losses. Our latest development is an in-house built data acquisition system with nanosecond time resolution (nanoDAQ). Recording of the SEM signal by the nanoDAQ is performed on the nanosecond time scale with a dwell time of approximately 2 ns and enables detection of gold nanoparticles (AuNP) as small as 7.5 nm with a commercial single quadrupole ICP-MS instrument. [1] Analysis of acquired transient data is based on the temporal distance between detector events and a derived ion event density. It was shown that the inverse logarithm of the distance between detector events is proportional to particle size. Also, the number of detector events per particle can be used to calibrate and determine the particle number concentration (PNC) of a nanoparticle dispersion. In addition to inorganic nanoparticles, first results on the detection of microplastics with spICP-MS will be discussed. T2 - ANAKON 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Nano KW - Microplastics KW - Nanoparticle Characterization KW - ICP-MS KW - Instrumentation PY - 2025 AN - OPUS4-63580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelhard, Carsten T1 - From Particles to PFAS: Recent Advances in Plasma-based Instrumentation Development N2 - In this presentation, recent advances in plasma spectrochemistry with hot and cold plasma sources for the direct detection of nanoparticles as well as per- and polyfluoroalkyl substances (PFAS) will be discussed. In the first part, single-particle inductively coupled plasma mass spectrometry (spICP-MS) with an in-house built data acquisition system with nanosecond time resolution (nanoDAQ) will be presented. In the second part, we turn to a cooler plasma source. Specifically, a flowing atmospheric-pressure afterglow source (FAPA) and its application for the direct mass spectrometric analysis of PFAS will be discussed. T2 - 20th European Winter Conference on Plasma Spectrochemistry CY - Berlin, Germany DA - 02.03.2025 KW - ICP-MS KW - Instrumentation KW - Nano KW - Nanoparticle Characterization KW - PFAS PY - 2025 AN - OPUS4-63581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chan, George C.-Y. A1 - Hieftje, Gary M. A1 - Omenetto, Nicoló A1 - Axner, Ove A1 - Bengtson, Arne A1 - Bings, Nicolas H. A1 - Blades, Michael W. A1 - Bogaerts, Annemie A1 - Bolshov, Mikhail A. A1 - Broekaert, José A.C. A1 - Chan, WingTat A1 - Costa-Fernández, José M. A1 - Crouch, Stanley R. A1 - De Giacomo, Alessandro A1 - D’Ulivo, Alessandro A1 - Engelhard, Carsten A1 - Falk, Heinz A1 - Farnsworth, Paul B. A1 - Florek, Stefan A1 - Gamez, Gerardo A1 - Gornushkin, Igor B. A1 - Günther, Detlef A1 - Hahn, David W. A1 - Hang, Wei A1 - Hoffmann, Volker A1 - Jakubowski, Norbert A1 - Karanassios, Vassili A1 - Koppenaal, David W. A1 - Kenneth Marcus, R. A1 - Noll, Reinhard A1 - Olesik, John W. A1 - Palleschi, Vincenzo A1 - Panne, Ulrich A1 - Pisonero, Jorge A1 - Ray, Steven J. A1 - Resano, Martín A1 - Russo, Richard E. A1 - Scheeline, Alexander A1 - Smith, Benjamin W. A1 - Sturgeon, Ralph E. A1 - Todolí, José-Luis A1 - Tognoni, Elisabetta A1 - Vanhaecke, Frank A1 - Webb, Michael R. A1 - Winefordner, James D. A1 - Yang, Lu A1 - Yu, Jin A1 - Zhang, Zhanxia T1 - Landmark Publications in Analytical Atomic Spectrometry: Fundamentals and Instrumentation Development N2 - The almost-two-centuries history of spectrochemical analysis has generated a body of literature so vast that it has become nearly intractable for experts, much less for those wishing to enter the field. Authoritative, focused reviews help to address this problem but become so granular that the overall directions of the field are lost. This broader perspective can be provided partially by general overviews but then the thinking, experimental details, theoretical underpinnings and instrumental innovations of the original work must be sacrificed. In the present compilation, this dilemma is overcome by assembling the most impactful publications in the area of analytical atomic spectrometry. Each entry was proposed by at least one current expert in the field and supported by a narrative that justifies its inclusion. The entries were then assembled into a coherent sequence and returned to contributors for a round-robin review. KW - Analytical atomic spectrometry KW - Spectroscopy KW - Instrumental analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621588 DO - https://doi.org/10.1177/00037028241263567 SN - 1943-3530 VL - 78 SP - 1 EP - 456 PB - Sage CY - London AN - OPUS4-62158 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -