TY - JOUR A1 - Kjaervik, Marit A1 - Müller, Anja A1 - Dietrich, P. A1 - Thissen, A. A1 - Bahr, S. A1 - Ritter, B. A1 - Kemnitz, E. A1 - Unger, Wolfgang T1 - Detection of suspended nanoparticles with near-ambient pressure x-ray photoelectron spectroscopy N2 - Two systems of suspended nanoparticles have been studied with near-ambient pressure x-ray photoelectron spectroscopy: silver nanoparticles in water and strontium fluoride—calcium fluoride core-shell nanoparticles in ethylene glycol. The corresponding dry samples were measured under ultra high vacuum for comparison. The results obtained under near-ambient pressure were overall comparable to those obtained under ultra high vacuum, although measuring silver nanoparticles in water requires a high pass energy and a long acquisition time. A shift towards higher binding energies was found for the silver nanoparticles in aqueous Suspension compared to the corresponding dry sample, which can be assigned to a change of surface potential at the water-nanoparticle interface. The shell-thickness of the core-shell nanoparticles was estimated based on simulated spectra from the National Institute of Standards and Technology database for simulation of electron spectra for surface analysis. With the instrumental set-up presented in this paper, nanoparticle suspensions in a suitable Container can be directly inserted into the analysis chamber and measured without prior sample preparation. KW - Nanoparticles KW - Suspensions KW - Core-shell nanoparticles KW - NAP-XPS PY - 2017 DO - https://doi.org/10.1088/1361-648X/aa8b9d SN - 1361-648X SN - 0953-8984 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. VL - 29 IS - 47 SP - 474002, 1 EP - 474002, 9 PB - IOP Publishing CY - UK AN - OPUS4-42951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Surface characterisation of bacteria and biofilms by NAP-XPS N2 - INTRODUCTION: X-ray photoelectron spectroscopy (XPS) provides elemental and chemical information from the outermost ~10 nm of the sample surface. This is in the same order of magnitude as the thickness of the outer bacterial membrane of gram-negative bacteria, as well as outer membrane molecules as exopolysaccharides and lipopolysaccharides, commonly attached to the cell surface. With the development of near-ambient pressure (NAP)-XPS, bacteria can be analysed with minimal sample preparation. This is in contrast to ultra-high vacuum XPS, where complex sample preparation including freeze-drying or fast-freezing is required, a treatment that may introduce artefacts or degrade the biological constituents. METHODS: EnviroESCA is a laboratory based NAP-XPS instrument, equipped with a monochromated Al Kα radiation source and a differentially pumped energy analyser connected to an exchangeable sample environment, a basic build-up is displayed in Figure 1c. It allows for measurements in various gas-atmospheres, including water vapor, which makes it possible to characterise bacteria and other biological samples close to their natural, hydrated state. Artificial model-biofilms of exopolysaccharides, planktonic Pseudomonas Fluorescens and biofilms of Escherichia Coli have been characterised in hydrated and dried state. RESULTS: High-resolution XPS-spectra from carbon, oxygen, nitrogen and phosphorous can be assigned to carbohydrates, lipids and proteins in general agreement with litterature2,3. Especially the carbon 1s peak is of interest (see Figure 1a and b), which reveal components originating from aliphatic carbon, single bounded carbon and double bounded/acetal carbon. A series of measurements of an E. coli biofilm from 11 mbar in humid environment to 1 mbar air reveal changes in the C1s peak, which suggests that the bacterial surface undergo substantial change. DISCUSSION & CONCLUSIONS: Bacterial samples can be analysed under near-ambient pressure conditions in various states of hydration with minimal sample preparation. Such investigations of bacterial cell wall surfaces are essential for studying biological interfaces at work. T2 - Biointerfaces International Conference CY - Zurich, Switzerland DA - 14.08.2018 KW - Bacteria KW - E. coli KW - NAP-XPS KW - Biofilms KW - Alginate PY - 2018 AN - OPUS4-45717 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Exploring the capabilities of near ambient pressure XPS: Characterisation of biofilms and nanoparticles in solution N2 - Seminar-talk for "Ausgewählte analytische Methoden der Physik " at TU Berlin. A introduction about near-ambient pressure XPS is given, furhter, results from measurements of biofilms and dispersed nanoparticles are presented and discussed. T2 - Seminar AG Kanngießer: Ausgewählte analytische Methoden der Physik CY - Technische Universität, Berlin, Germany DA - 04.07.2017 KW - Alginate KW - NAP-XPS KW - Nanoparticles KW - Biofilms KW - E. coli PY - 2017 AN - OPUS4-40905 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Stability and homogeneity of alginate samples N2 - Overview of measurements and future work regarding near ambient pressure XPS on alginate samples relevant for the EMPIR-project MetVBadBugs- Quantitative measurement and imaging of drug-uptake by bacteria with antimicrobial resistance. T2 - MetVBadBugs 18M Meeting CY - PTB, Berlin, Germany DA - 17.07.2017 KW - Alginate KW - NAP-XPS KW - Biofilms PY - 2017 AN - OPUS4-41077 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Characterisation of biofilms with near-ambient pressure XPS N2 - A drawback for X-ray photoelectron spectroscopy is that the measurements must be performed under ultra-high vacuum, which limits the type of samples which can be studied. However, by applying a differentially pumped aperture positioned close to the surface, even wet samples can be measured at near ambient pressure while the energy analyser is still under ultra-high vacuum, as illustrated below. Successful XPS-measurements with pressure up to 30 mbar have been reported using this approach, which opens up a new world of possibilities for ambient pressure measurements with XPS. While there are examples where NAP-XPS has been used to study electrochemical processes and heterogeneous catalysis, little attention has been paid to its potential use in biological materials. Until now, bacteria have only been characterised with conventional XPS, which requires tedious sample preparation usually involving freeze drying, a treatment that may degrade biological sample constituents. By studying biological samples in their native wet states, new insight about composition, absorption and transport of drugs through cell membranes and extracellular polymeric substance (EPS) layers can be obtained. Both artificial model-films of exopolysaccharides and biofilms of Escherichia Coli have been characterised at pressures ranging from ultra-high vacuum to 15 mbar by using SPECS’ EnviroESCA NAP-XPS instrument and conventional XPS. By applying antimicrobials to model biofilms, some of which are known to be resistant towards the antimicrobial in question, the distribution of antimicrobials in biofilms has been studied. Measurement capabilities and limitations of the approach will be discussed. T2 - European conferene on applications of surface and interface analysis (ECASIA 17) CY - Montpellier, France DA - 25.09.2017 KW - NAP-XPS KW - E. coli KW - Biofilms KW - Alginate PY - 2017 AN - OPUS4-42561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Characterization of biofilms with near ambient pressure XPS N2 - Near Ambient Pressure XPS opens up a new world of possibilities for measurements with XPS. While there are examples where NAP-XPS has been used to study electrochemical processes and heterogeneous catalysis, little attention has been paid to its potential use in biological materials. Until now, bacteria have only been characterised with conventional XPS, which requires tedious sample preparation usually involving freeze drying, a treatment that may degrade biological sample constituents. By studying biological samples in their native wet states, new insight about composition, absorption and transport of drugs through cell membranes and extracellular polymeric substance (EPS) layers can be obtained. Both artificial model-films of exopolysaccharides and biofilms of Escherichia Coli have been characterised at pressures ranging from ultra-high vacuum to 15 mbar by using SPECS’ EnviroESCA NAP-XPS instrument and conventional XPS. By applying antimicrobials to model biofilms, some of which are known to be resistant towards the antimicrobial in question, the distribution of antimicrobials in biofilms has been studied. Capabilities and limitations of the approach will be discussed. T2 - The 4th annual workshop on ambient presssure X-ray photoelectron spectroscopy CY - Shanghai, China DA - 13.12.2017 KW - NAP-XPS KW - Biofilms KW - E. coli PY - 2017 AN - OPUS4-43568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Surface characterisation of biofilms by nearambient pressure X-ray photoelectron spectroscopy N2 - The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained. T2 - Royal Society of Chemistry Twitter Conference CY - Worldwide (online conference) DA - 06.03.2018 KW - Biofilms KW - E. coli KW - Alginate KW - NAP-XPS PY - 2018 AN - OPUS4-44498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Progress on characterisation of biofilms by NAP-XPS N2 - Progress talk on characterisation of biofilms by NAP-XPS in the framework of the MetVBadBugs EURAMET-project T2 - MetVBadBugs 24 M project meeting CY - Turin, Italy DA - 06.02.2018 KW - Biofilms KW - E. coli KW - Alginate KW - NAP-XPS PY - 2018 AN - OPUS4-44065 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Surface characterisation of biological samples with near-ambient pressure XPS N2 - The principle of NAP-XPS is explained, together with its relevance for biological samples. Further, ongoing work on NAP-XPS measurements on E. coli biofilms is presented. T2 - Seminar AG Weinhart, FU Berlin CY - Freie Universität, Berlin, Germany DA - 05.12.2016 KW - NAP-XPS KW - Biofilms KW - Alginate KW - E. coli PY - 2017 AN - OPUS4-43331 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit A1 - Seim, C. T1 - EMPIR project Metrology vs. Bad Bugs aims to provide urgently needed metrology to quantitatively measure localization and penetration of antibiotics and biocides in bacteria and biofilms N2 - An overview of ongoing reference-free X-ray spectrometry, near-ambient pressure X-ray photoelectron spectroscopy and Fourier-Transform infrared micro-spectroscopy studies on the penetration of biocides/antibiotics into bacteria and biofilms is given. T2 - Ninth Joint BER II and BESSY II User Meeting CY - Berlin, Germany DA - 13.12.2017 KW - Biofilms KW - Alginate KW - XRF KW - FTIR KW - NAP-XPS PY - 2017 AN - OPUS4-43465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Surface characterisation of biological samples by near-ambient pressure XPS N2 - A presentation held for the seminar "Ausgewählte analytische Methoden der Physik" hosted by Prof. Birgit Kanngießer at TU Berlin. The first part focus on depth-dependent XPS-measurements (XPS, synchrotron HAXPES) to obtain a concentration profile of iodine in an artificial biofilm. In the second part, NAP-XPS measurements of various bacterial samples are presented. T2 - Forschungsseminar "Ausgewählte analytische Methoden der Physik", TU Berlin CY - Berlin, Germany DA - 17.07.2018 KW - Biofilms KW - Alginate KW - Agarose KW - HAXPES KW - NAP-XPS PY - 2018 AN - OPUS4-45505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Near-ambient pressure XPS of hydrated Escherichia coli samples with EnviroESCA N2 - This application note presents how EnviroESCA can be used to analyze E. coli biofilms on silicon under near ambient pressure conditions in various states of hydration. Such investigations of the outer bacterial cell surface in their hydrated state are essential for studying biological interfaces at work. KW - Biofilms KW - E. coli KW - NAP-XPS PY - 2018 UR - http://www.enviroai.com/uploads/1/0/2/8/102861712/nap_xps_of_escherichia_coli_samples.pdf IS - Application Note #000400 SP - 1 EP - 4 CY - Berlin, Germany AN - OPUS4-45720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Surface characterisation of bacteria and biofilms by NAP-XPS N2 - The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained. In this contribution, the latest progress on biofilm characterisation by NAP-XPS will be presented, and measurement capabilities and limitations will be discussed. T2 - Die Frühjahrstagung der Deutsche Physikalische Gesellschaft CY - Berlin, Germany DA - 12.03.2018 KW - Biofilms KW - E. coli KW - Alginate KW - NAP-XPS PY - 2018 AN - OPUS4-44500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P.M. A1 - Unger, Wolfgang T1 - NAP-XPS spectra of the bacterial cell-envelope of Pseudomonas fluorescens bacteria N2 - Pseudomonas fluorescens (Gram-negative) bacteria purchased from Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures were analyzed using high-resolution x-ray photoelectron spectroscopy at near ambient pressure conditions (NAP-XPS), 1500 Pa water vapor atmosphere. Fresh layers of P. fluorescence bacteria were grown on Luria Broth agar plates. Bacteria were taken from the agar plate with a sterile spatula and gently spread on a Si-wafer piece for NAP-XPS analysis. The NAP-XPS spectra of the bacterial envelope of P. fluorescence were obtained using monochromatic Al Kα radiation and include a survey scan and high-resolution spectra of C 1s, N 1s, P 2p, and O 1s as well. The presentation of the C 1s high-resolution spectrum includes the results of peak fitting analysis. KW - Pseudomonas fluorescens KW - Cell-envelope KW - Water atmosphere KW - Near ambient x-ray photoelectron spectroscopy KW - NAP-XPS PY - 2022 DO - https://doi.org/10.1116/6.0001543 SN - 1055-5269 VL - 29 IS - 1 SP - 014008-1 PB - AVS AN - OPUS4-54464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Ramstedt, M. A1 - Schwibbert, Karin A1 - Dietrich, P. M A1 - Unger, Wolfgang T1 - Comparative Study of NAP-XPS and Cryo-XPS for the Investigation of Surface Chemistry of the Bacterial Cell-Envelope N2 - Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems. KW - P. Fluorescens KW - Cryo XPS KW - NAP-XPS KW - DSM 5009 PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525640 DO - https://doi.org/10.3389/fchem.2021.666161 VL - 9 SP - Article 666161 PB - Frontiers CY - Switzerland AN - OPUS4-52564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS N2 - Bacteria are inherently in a hydrated state and therefore not compatible to ultra-high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing. This has changed with the development of near-ambient pressure (NAP)-XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP-XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre-dried at 4 mbar, and at 1 mbar after overnight pumping at 10^−4 mbar. The high-resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze-dried and fast-frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface. T2 - European conference on applications of surface and interface analysis (ECASIA'17) CY - Montpellier, France DA - 24.09.2018 KW - Bacteria KW - E. coli KW - NAP-XPS PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454047 DO - https://doi.org/10.1002/sia.6480 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 11 SP - 996 EP - 1000 PB - John Wiley & Sons CY - Hoboken, New Jersey, USA AN - OPUS4-45404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Investigations of biofilms in various conditions by near-ambient pressure XPS N2 - X-ray photoelectron spectroscopy (XPS) provides elemental and chemical information from the outermost ~10 nm of the sample surface. This is in the same order of magnitude as the thickness of the outer bacterial membrane of gram-negative bacteria, as well as outer membrane molecules as exopolysaccharides and lipopolysaccharides, commonly attached to the cell surface. With the development of near-ambient pressure (NAP)-XPS, bacteria can be analysed with minimal sample preparation. EnviroESCA is a laboratory based NAP-XPS instrument, equipped with a monochromated Al Kα radiation source and a differentially pumped energy analyser connected to an exchangeable sample environment. It allows for measurements in various gas-atmospheres, including water vapor, which makes it possible to characterise bacteria and other biological samples close to their natural, hydrated state. Artificial model-biofilms of exopolysaccharides, planktonic Pseudomonas Fluorescens and biofilms of Escherichia Coli have been characterised in hydrated and dried state. High-resolution XPS-spectra from carbon, oxygen, nitrogen and phosphorous can be assigned to carbohydrates, lipids and proteins in general agreement with literature. Especially the carbon 1s peak is of interest. A series of measurements of an E. coli biofilm from 11 mbar in humid environment to 1 mbar air reveal changes in the C1s peak, which suggests that the bacterial surface undergo substantial Change. T2 - BAM PhD-retreat CY - Warnemünde, Germany DA - 28.09.2018 KW - Biofilms KW - E. coli KW - NAP-XPS PY - 2018 AN - OPUS4-46132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Exploring the capabilities of NAP-XPS: Application to metal-organic frameworks, nanoparticles and biofilms N2 - Near-ambient pressure XPS makes it possible to characterise samples not compatible to ultra-high vacuum, and enables the study of liquid-solid, gas-liquid and gas-solid interfaces. NAP-XPS meas-urements of biofilms, suspended nanoparticles and metal-organic frameworks were performed with EnviroESCA developed by SPECS. An interesting application is surface characterisation of biofilms, which are bacterial communities embedded in a self-produced polysaccharide matrix. Various model systems ranging from pure polysaccharides of alginate to biofilms harvested directly from the growth medium have been char-acterised in humid conditions[1]. NAP-XPS also makes it possible to characterise nanoparticles in solution. Silver nanoparticles in aqueous solution were characterised and the Ag 3d-spectrum compared to spectra obtained of dried nanoparticles in UHV-conditions[2]. The binding energy of the Ag 3d-core level peak was shifted by 0,6 eV towards higher binding energy for suspended nanoparticles compared to the dried sample measured in UHV. This can be assigned to a change in surface potential at the water-nanoparticle interface. Metal-organic frameworks (MOFs) are suitable materials for gas storage of small molecules due to their nanoporous, crystalline structure. However, instability in humidity remains an issue for many types of MOFs. XPS-measurements of the MOF-structure HKUST-1 were performed in various NAP-conditions to assess the stability of the sample and its interaction with the gas molecules as water, methanol and pyridine. T2 - 5th AP-XPS Workshop CY - Berlin, Germany DA - 11.12.18 KW - Biofilms KW - E. coli KW - NAP-XPS KW - Metal organic frameworks KW - Nanoparticles PY - 2018 AN - OPUS4-47060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Model systems and sample preparation for surface characterisation of bacteria and biofilms by near-ambient pressure XPS N2 - Bacterial samples are typically freeze dried or cryo-prepared prior to XPS analysis to allow for measurements in ultra-high vacuum (UHV). The sample environment in the near-ambient pressure (NAP) XPS instrument EnviroESCA allows for measurements in up to 15 mbar water vapor, thus, sample preparation is no longer restricted to UHV-compatible techniques. For instance, biofilms grown in medium can be transferred directly from the medium to the measurements chamber, maintaining a humid environment throughout the measurements. Considering the complexity of bacterial samples, sample preparation must be carefully considered in order to obtain meaningful and reproducible results. In this talk, various strategies for sample preparation of bacteria and biofilms for NAP-XPS measurements will be discussed. Model systems of planktonic bacteria, artificial biofilms resembling the exopolysaccharide matrix and biofilms have been characterised in various conditions. The stability and homogeneity of the samples was assessed by monitoring the C1s core level peak at different sample locations. The quality of the XPS-spectra is also influenced by the gas environment, which will be exemplified by core level spectra of P. Fluorescens acquired in air, water vapor and ultra-high vacuum. T2 - 18th European conference on applications of surface and interface analysis (ECASIA) CY - Dresden, Germany DA - 15.09.2019 KW - NAP-XPS KW - Biofilms KW - Bacteria KW - E. coli KW - XPS PY - 2019 AN - OPUS4-49189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jain, V. A1 - Kjaervik, Marit A1 - Bahr, S. A1 - Dietrich, P. A1 - Meyer, M. A1 - Thissen, A. A1 - Linford, M. R. T1 - Bovine serum albumin, aqueous solution, by near-ambient pressure XPS N2 - Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, C 1s, O 1s, and N 1s narrow scans from an aqueous solution of a common protein, bovine serum albumin. The C 1s peak envelope is well fit to four symmetric peaks of equal width that correspond to carbon bonded to carbon and hydrogen (C-1), carbon singly bonded to oxygen (C-2), carbonyl and/or amide carbon (C-3), and carboxyl carbon (C-4). Two possible peak fits are considered for the N 1s and O 1s peak envelopes. The N 1s signal is fit to four peaks that correspond to amine (—NH2), Amide (OvCZNH2), ammonium (—NH3 +), and N2(g) nitrogen, and alternatively to three peaks that correspond to amine, amide, and N2(g) nitrogen. The O 1s peak envelope is similarly fit to three and four components. KW - NAP-XPS KW - BSA KW - Bovine serum albumin KW - XPS KW - Near-ambient pressure PY - 2019 DO - https://doi.org/10.1116/1.5055229 VL - 26 IS - 1 SP - 014027 PB - American Vacuum Society CY - New York, USA AN - OPUS4-48655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Investigations of HKUST-1 exposed to water vapor, methanol and pyridine atmospheres by near-ambient pressure XPS N2 - Metal-organic frameworks (MOFs) are suitable materials for gas storage of small molecules due to their nanoporous, crystalline structure. The extensively studied MOF HKUST-1 consist of Cu(II)-dimers in a paddlewheel structure, with 1,3,5-benzenetricarboxylic acid (BTC) as organic linker. Instability to humidity remains an issue for many types of MOFs, and for HKUST-1, it has been found that exposure to water vapor creates a surface barrier which reduces the gas uptake rate. Near-ambient pressure XPS (NAP-XPS) is a promising method for investigations of the stability and interaction of HKUST-1 with various gas molecules. The oxidation state of copper can be monitored before, during and after exposure to various gases. This does not only provide information on the stability of the MOFs, but also on the interaction with the gas molecules. NAP-XPS measurements of HKUST-1 exposed to methanol, pyridine and water vapor were performed with EnviroESCA, a laboratory NAP-XPS instrument developed by SPECS. Cu 2p, O 1s and C 1s core level spectra and Cu LMM Auger spectra were acquired at pressures ranging from high vacuum to 4 mbar to assess the oxidation state of copper and the stability of the organic linker. Reference measurements in argon atmosphere were conducted in order to have reference spectra with similar full width of half maxima (FHWM) as the spectra measured in reactive atmospheres. Peak fit analysis of the Cu 2p3/2 core level spectra shows that, as expected, the photoelectron signal mainly originates from Cu(II) species. The contribution from Cu(I) is negligible for samples exposed to argon and methanol, but approximately 4% for samples exposed to water vapor and 8% for samples exposed to pyridine. Within the error of the peak fit analysis, there are no changes in relative Cu(II) percentage with increasing water, methanol or pyridine exposure time pointing to saturation reached already at the lowest time of exposure. T2 - Seminar X-Ray and Electron Spectroscopy at Interfaces group: Chemistry of oxydic and organic interfaces CY - Karlsruhe, Germany DA - 11.10.2019 KW - XPS KW - MOF KW - HKUST-1 KW - NAP-XPS PY - 2019 AN - OPUS4-49289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Investigations of HKUST-1 exposed to argon, pyridine, methanol and water vapor by near-ambient pressure XPS N2 - Metal-organic frameworks (MOFs) are suitable materials for gas storage of small molecules due to their nanoporous, crystalline structure. The extensively studied MOF HKUST-1 consist of Cu(II)-dimers in a paddlewheel structure, with 1,3,5-benzenetricarboxylic acid (BTC) as organic linker. Instability to humidity remains an issue for many types of MOFs, and for HKUST-1, it has been found that exposure to water vapor creates a surface barrier which reduces the gas uptake rate. Near-ambient pressure XPS (NAP-XPS) is a promising method for investigations of the stability and interaction of HKUST-1 with various gas molecules. The oxidation state of copper can be monitored before, during and after exposure to various gases. This does not only provide information on the stability of the MOFs, but also on the interaction with the gas molecules and the reversibility of the processes. NAP-XPS measurements of HKUST-1 exposed to methanol, pyridine and water vapor were performed with EnviroESCA, a laboratory NAP-XPS instrument developed by SPECS. Cu 2p, O 1s and C 1s core level spectra were acquired in pressure ranging from 10-5 to 8 mbar to assess the oxidation state of copper and the stability of the organic linker. HKUST-1 does not show interaction with pyridine, but there are indications of copper-reduction upon exposure to methanol and water vapor. Radiation induced damage is considered and two different approaches for determining the ratio of Cu(I) to Cu(II) will be discussed. T2 - Bunsentagung 2019 - 118th General Assembly of the German Bunsen Society for Physical Chemistry CY - Jena, Germany DA - 30.05.2019 KW - XPS KW - MOF KW - HKUST-1 KW - NAP-XPS KW - Metal organic frameworks PY - 2019 AN - OPUS4-48195 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kjaervik, Marit T1 - Quantitative biocide profile measurements by calibrated XPS N2 - This presentation provides an update on recent results from quantitative XPS-measurements of real and artificial biofilms. NAP-XPS, lab-based XPS and synchrotron-based XPS was used to obtain a vertical concentration profile of iodine in agarose-films with information depth ranging from 1 to 18 nm. T2 - Project meeting MetVBadBugs CY - Turin, Italy DA - 05.02.2019 KW - Biofilms KW - NAP-XPS KW - XPS KW - Iodine KW - Agarose PY - 2019 AN - OPUS4-47332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -