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EnviroESCA

Electron Spectroscopy for Chemical Analysis under Environmental Conditions Allows the Near Ambient Pressure (NAP) XPS Analysis of Catalysts, Liquids and Liquid-Solid Interfaces.

The SPECS EnviroESCA is  a novel and smart analysis tool, that overcomes the barriers of standard XPS systems by enabling analyses at pressures far above UHV. EnviroESCA is designed for high-throughput analysis and opens up new applications in the fields of medical technology, biotechnology and the life sciences. It offers the shortest loading-to-measurement time on samples of all types including liquids, tissue, plastics and foils, powders, soil, zeolites, rocks, minerals and ceramics.

KEY FEATURES

  • Fast Quality Control 
  • High Throughput Analysis
  • Controllable Atmosphere
  • Revolutionary Technology
  • Ergonomic all-in-one Design
  • Fully Software Controlled

MADE FOR THESE METHODS

1

APPLICATION NOTES

AP-XPS investigations of a commercial lithium-based electrolyte
AP-XPS investigations of a commercial lithium-based electrolyte
In this note we present first AP-XPS results from a commercial liquid electrolyte for lithium ion battery production recorded at 10 mbar in the EnviroESCA. The solution is LiPF6 in EC/DMC as a common battery electrolyte. First we analyzed the LiPF6 solution in its vapor and liquid phase. In a second step we immersed V2O5, a typical cathode material, in this solution. Photoelectron spectra show significant chemical differences on the studied surfaces. This proof of principle study shows the enormous potential of the EnviroESCA for AP-XPS investigations of solid-liquid interfaces and the simplicity of the experimental setup.
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Investigation of Polymers and Plastics with EnviroESCA
Investigation of Polymers and Plastics with EnviroESCA
This application note describes how EnviroESCA can be used to analyze the surface of polymers and bulk insulating material. EnviroESCAs ability to perform X-Ray Photoelectron Spectroscopy (XPS) at non vacuum conditions shows its main advantage when being applied to insulating material. Specimens that tend to charge up under vacuum conditions and need to be extensive charge compensated with expensive low energy electron and low energy ion sources can be measured with ease and without the problem of overcompensation.
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Investigation of a Superabsorbent Polymer (SAP) with EnviroESCA
Investigation of a Superabsorbent Polymer (SAP) with EnviroESCA
In this study we show how EnviroESCA can be used to analyze the surface of superabsorbent polymers under different environmental conditions. EnviroESCA’s ability to perform X-ray Photoelectron Spectroscopy (XPS) under ambient conditions shows its main advantage when being applied to insulating material that change their surface (chemistry) when they come in contact with different liquids and gases - in this case water. Specimens that tend to charge up under vacuum conditions can be measured with ease.
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XPS surface chemical analysis of aqueous solutions with EnviroESCA
XPS surface chemical analysis of aqueous solutions with EnviroESCA
In this study we present the capabilites of EnviroESCA to analyze the surface of various aqueous solutions under near ambient pressure conditions. Such investigations of aqueous solutions are of paramount importance due to the vast number of essential water based processes in nature and industry.
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XPS surface analysis of a human urolith with EnviroESCA
XPS surface analysis of a human urolith with EnviroESCA
A single human urinary stone (urolith) was characterized using EnviroESCA. The result of surface chemical analysis of the as received samples is presented. Charge neutralization on this insulating material is accomplished by Environmental Charge Compensation.
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XPS surface analysis of human tooth samples with EnviroESCA
XPS surface analysis of human tooth samples with EnviroESCA
Human teeth from an adult and a baby were studied using EnviroESCA. The results of surface chemical analysis of the as-received human tissues samples are presented. Neutralization of the insulating bio-material is accomplished by Environmental Charge Compensation enabling X-ray Photoelectron Spectroscopy (XPS) on tissues as tooth or bone.
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XPS surface analysis of cuttlefish bone samples with EnviroESCA
XPS surface analysis of cuttlefish bone samples with EnviroESCA
Biological mineral samples from a cuttlefish (sepia) were studied using EnviroESCA. The results of surface chemical analysis of the native and ion implantation treated samples are presented. Neutralization of the insulating biomaterial is accomplished by Environmental Charge Compensation enabling X-ray Photoelectron Spectroscopy (XPS) on tissue samples.
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XPS surface analysis of V2O5 upon heating with EnviroESCA
XPS surface analysis of V2O5 upon heating with EnviroESCA
This application note presents how EnviroESCA can be used to analyze samples during heating under near ambient pressure conditions using various gas atmospheres. Such investigations of surfaces at elevated temperatures and pressures are of paramount importance for catalysis in nature and industry.
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XPS surface chemical analysis of bacterial samples with EnviroESCA
XPS surface chemical analysis of bacterial samples with EnviroESCA
This application note presents how EnviroESCA can be used to analyze bacterial samples under near ambient pressure conditions in various states of hydration using different levels of humidity. Such investigations of bacterial cell wall surfaces in their hydrated state are essential for studying biological interfaces at work.
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Near-ambient pressure XPS of hydrated Escherichia coli samples with EnviroESCA
Near-ambient pressure XPS of hydrated Escherichia coli samples with EnviroESCA
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.
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Gas Cluster Ion Beam (GCIB) sputtering with EnviroESCA
Gas Cluster Ion Beam (GCIB) sputtering with EnviroESCA
This application note presents how the optional GCIB source at the EnviroESCA can be used to clean samples prior to XPS analysis to get reproducible analytical data and reliable quantification results. Moreover, Argon cluster Arn⁺ (n=500-5000) sputtering and depth profiling of (bio)organic samples is possible which cannot be done when using monoatomic Arn+ sputtering.
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XPS surface analysis of Italian hard cheese with EnviroESCA
XPS surface analysis of Italian hard cheese with EnviroESCA
This application note presents how EnviroESCA can be used to analyze the surface of food samples, e.g., Italian hard cheese. Due to the advanced vacuum system of EnviroESCA the surface analysis of Food samples even in the presence of fat and oils or volatiles is performed without problems.
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XPS surface analysis of printed paper samples with EnviroESCA
XPS surface analysis of printed paper samples with EnviroESCA
Results of the surface analysis of four paper samples obtained in EnviroESCA are presented. Neutralization of this insulating biopolymer is accomplished by Environmental Charge Compensation enabling X-ray Pho-toelectron Spectroscopy (XPS) on such important natural material with ease.
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Real World Device Inspection Application with EnviroESCA
Real World Device Inspection Application with EnviroESCA
This application note introduces EnviroESCA as a tool for real world device inspection for microelectronics. A printed circuit board was taken directly from the sales packaging and was investigated with XPS. The measurements concentrate on the crucial parts like contact surfaces and soldering joints. EnviroESCA and near ambient pressure XPS (NAP-XPS) in quality control applications aims to optimize manufacturing processes and device quality in general.
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Investigation of Hydrogel Contact Lenses with EnviroESCA
Investigation of Hydrogel Contact Lenses with EnviroESCA
In this application note we analyze the surface of water filled hydrogels with EnviroESCA, Here, contact lenses serve as an example for medical and biomaterials. The advantage of such investigations under non ultrahigh vacuum conditions is demonstrated and results from wet and dry samples are compared.
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XPS surface analysis of Zeolites with EnviroESCA
XPS surface analysis of Zeolites with EnviroESCA
In this note we demonstrate how the surface of Clinoptilolite, a natural zeolite, can be analysed with EnviroESCA. It describes how the Environmental Charge Compensation can be used to compensate for charging of the sample surface to be able to measure X-ray Photoelectron Spectra with ease.
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XPS surface analysis of a leaf with EnviroESCA
XPS surface analysis of a leaf with EnviroESCA
This application note presents the application of EnviroESCA to the field of biology and surface spectroscopy of biological samples. X-ray Photoelectron Spectroscopy (XPS) measurements on different sites of a leaf will be discussed. It will be shown that XPS is able to detect residues of calcium chloride, being used as a fertilizer, on the leafs surface.
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EnviroESCA and NAP-XPS in the field of Cosmetic Science
EnviroESCA and NAP-XPS in the field of Cosmetic Science
This application note presents the application of EnviroESCA to the field of Cosmetic Sciences and Forensic Sciences. Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) measurements on human hair treated with different personal hair care products.
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EnviroESCA applications in Scientific Archaeology
EnviroESCA applications in Scientific Archaeology
In the present application note EnviroESCA is used for chemical Analysis in the field of Archaeometry. Besides the ability of Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) to analyze the surface composition of metallic and nonmetallic specimens, EnviroESCA allows for a nondestructive analysis of artifacts without special pretreatment procedures.
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XPS surface analysis of a coffee bean with EnviroESCA
XPS surface analysis of a coffee bean with EnviroESCA
The Analysis of food and natural products under environmental conditions is of great importance due to their daily use and direct interaction with humans during consumption. In this study we investigated a roated coffee bean. Charge compensation of this insulating natural product is accomplished by Environmental Charge Compensation enabling X-ray photoelectron spectroscopy on such biological material with ease.
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XPS surface analysis of an ionic liquid with EnviroESCA
XPS surface analysis of an ionic liquid with EnviroESCA
This application note presents how EnviroESCA can be used to analyze the surface of ionic liquids in contact with gases under application relevant conditions in the near ambient pressure region.
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XPS surface analysis of sesame seeds with EnviroESCA
XPS surface analysis of sesame seeds with EnviroESCA
Results of the surface analysis of untreated food samples, e.g., sesame seeds, measured with EnviroESCA are presented. High resolution and high quality spectra are recorded using Environmental Charge Compensation even for samples in bulk quantities.
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Corrosion study of a paper clip in vinegar with EnviroESCA
Corrosion study of a paper clip in vinegar with EnviroESCA
In this note we present (N)AP XPS results from the first comparative ex-situ and operando corrosion study on the reaction of commercial paper clips in concentrated vinegar solution containing 25% acetic acid.
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PUBLICATIONS

  1. (2020) Polyethylene terephthalate by near-ambient pressure XPS

    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, and O 1s NAP-XPS spectra of polyethylene terephthalate, a common, widely used thermoplastic. The C 1s envelope was fit with different approaches, i.e., to three, four, and five Gaussian–Lorentzian sum (GLS) functions. Hartree–Fock orbital energy calculations of a model trimer served as a guide to an additional fit of the C 1s envelope. The best fit was obtained by adding an extra component to the four-component fit to compensate for adventitious carbon or additives in the polymer. The O 1s signal was well fit with two GLS peaks with a 1:1 area ratio representing the C—O and C=O moieties in PET.



    Tahereh G. Avval, Grant T. Hodges, Joshua Wheeler, Daniel H. Ess, Stephan Bahr, Paul Dietrich, Michael Meyer, Andreas Thißen, and Matthew R. Linford
    Surface Science Spectra 27, 014006 (2020)
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  2. (2020) Roman coin, by near-ambient pressure XPS

    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, O 1s/Ag 3p, Ca 3p/Ag 3d, and extended valence band (0–130 eV) NAP-XPS spectra of an ancient Roman coin at three different positions. A small N 1s signal from N2 background gas is also observed. On the obverse side, the coin bears the bust of Licinius I. On the reverse side, it bears the image of Jupiter. The Ag 3d region indicates different amounts of silver at different oxidation states in different positions.



    Tahereh G. Avval, Sean C. Chapman, Jeffrey T. Chapman, Stephan Bahr, Paul Dietrich, Michael Meyer, Andreas Thißen, and Matthew R. Linford
    Surface Science Spectra 27, 014022 (2020)
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  3. (2020) Evidence for a core-shell structure of hydrothermal carbon

    Hydrothermal carbonisation (HTC) has been demonstrated to be a sustainable thermochemical process,
    capable of producing functionalised carbon materials for a wide range of applications. In order to better
    apply such materials, the local chemistry and reaction pathways governing hydrothermal carbon growth
    must be understood. We report the use of scanning transmission X-ray microscopy (STXM) to observe
    chemical changes in the functionality of carbon between the interface and bulk regions of HTC. Spatiallyresolved,
    element-specific X-ray photo-absorption spectra show the presence of differing local carbon
    chemistry between bulk “core” and interface “shell” regions of a glucose-derived hydrothermal carbon
    spherule. STXM provides direct evidence to suggest that mechanistic pathways differ between the core
    and shell of the hydrothermal carbon. In the shell region, at the water-carbon interface, more aldehyde
    and/or carboxylic species are suspected to provide a reactive interface for bridging reactions to occur
    with local furan-based monomers. In contrast, condensation reactions appear to dominate in the core,
    removing aryl-linking units between polyfuranic domains. The application of STXM to HTC presents
    opportunities for a more comprehensive understanding of the spatial distribution of carbon species
    within hydrothermal carbon, especially at the solvent-carbon interface.



    L.J.R. Higgins, A. P. Brown, J. P. Harrington, A. B. Ross, B. Kaulich and B. Mishra
    Carbon 161 (2020) 423-431
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  4. (2020) Biocompatible pure ZnO nanoparticles-3D bacterial cellulose biointerfaces with antibacterial properties

    In this paper, we present for the first time the obtaining and characterization of new antibacterial and biocompatible nano-ZnO–bacterial cellulose (BC) material with controlled interfaces for studying in vitro microorganisms (Escherichia Coli (ATCC 8737), B. subtilis Spizizenii Nakamura (ATCC 6633), Candida albicans (ATCC10231)) and mammalian cells (human dermal fibroblast cells) response. The use of BC based material with controlled characteristics in terms of quantity and distribution of ZnO onto BC membrane (with 2D and 3D fibers arrangement) is directly correlated with the surface chemical and topographical properties, the method of preparation, and also with the type of cells implied for the specific application within the bioengineering fields. In our study, the uniform distribution and the control on the quantity of ZnO nanoparticles onto 3D BC were obtained using matrix assisted pulsed laser evaporation (MAPLE) method. The influence on particle distribution onto 3D bio cellulose were investigated based on two types of solvents (water and chloroform) involved in target preparation within MAPLE deposition. The attachment of the nanoparticles to the bacterial cellulose surface and fibrils was demonstrated by SEM and FT-IR studies. The BC-ZnO showed both resistance to bacteria-sticking and non-cytotoxic effect on the human dermal fibroblasts cells at a mass distribution onto surface of 1.68 µg ZnO NPS/mm2. These results represent a good premise in terms of tailoring BC substrates with ZnO particles that could determine or enhance both the biocompatibility and antibacterial properties of BC-composite materials.



    V. Dinca, A. Mocanu, G. Isopencu, C. Busuioc, S. Brajnicov, A. Vlad, M. Icriverzi, A. Roseanu,
    M. Dinescu, M. Stroescu, A. Stoica-Guzun, M. Suchea
    Arabian Journal of Chemistry
    Volume 13, Issue 1, January 2020, Pages 3521-3533
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  5. (2020) Highly efficient Cu/SiO2 catalyst derived from ethanolamine modification for furfural hydrogenation

    The production of furfuryl alcohol from furfural hydrogenation in gas
    phase is of great significance for the valorization of biomass. The existing catalyst for
    this transformation suffers from high cost and complex preparation process. Thus, a
    highly efficient copper catalyst was developed by a simple impregnation method
    using ethanolamine modified granular silica as carrier.
    The catalytic performance was related to the amount of ethanolamine used in modification.
    Highly dispersed copper with uniform particle size distribution was obtained from appropriate amount of
    ethanolamine modified granular silica. The ethanolamine modified granular silica
    (mass ratio between ethanolamine and silica was 3 in the initial modification mixture)
    supported copper catalyst exhibited the best performance in terms of catalyst lifetime
    thanks to its maximum amount of Cu0 sites and largest amount of Cu+ sites. A slow
    deactivation of the catalyst after extended time on stream evaluation is attributed to
    carbon deposition and slow copper sintering.



    H. Du, X. Ma, M. Jiang, P. Yan and Z. C. Zhang
    Applied Catalysis A, General
    APCATA 117598
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  6. (2020) Effects of Background Gas Composition and Pressure on 1,4-Polymyrcene (and Polytetrafluoroethylene) Spectra in near-ambient pressure XPS

    Near-ambient pressure XPS (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500 Pa or greater. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s and survey NAP-XPS spectra from 1,4-polymyrcene. The C 1s and O 1s envelopes are fit with Gaussian-Lorentzian product, asymmetric Lorentzian, and Gaussian-Lorentzian sum functions, respectively. Water vapor and argon are used to control sample charging, and the corresponding signals from the gases are present in the survey spectra. The effect of background gas pressure on photoelectron attenuation is illustrated with a sample of polytetrafluoroethylene.



    Dhananjay I. Patel, Aleksandar Matic, Helmut Schlaad, Stephan Bahr, Paul Dietrich, Michael Meyer, Andreas Thißen, Sven Tougaard, and Matthew R. Linford
    Surface Science Spectra (Vol.27, Issue 1)
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  7. (2020) Modulating electronic structure of graphene overlayers through electrochemical intercalation

    Modulating electronic structure of graphene overlayers is highly demanding for its potential applications in
    microelectronics, sensors, and catalysis, which however remains a grand challenge. Here, we report electrochemistry-
    involved treatments to tune the electronic structure of graphene overlayers. Both galvanic corrosion
    and potential-aided intercalation of H2O were employed to change the graphene/Cu interfaces to graphene/
    Cu2O/Cu and graphene/H2O/Cu interfaces, respectively. Electronic properties and structural changes of the
    graphene/Cu interfaces were investigated by X-ray photoelectron spectroscopy, in-situ Raman, and atomic force
    microscopy. The formed Cu2O interlayer blocks the charge transfer between graphene overlayer and Cu substrate,
    which turns n-type doping of the as-grown graphene to free-standing state. In contrast, the intercalated
    H2O interlayer induces much stronger n-type doping in graphene through the electrostatic field effect generated
    by confined H2O. This work offers efficient but mild methods to modulate the doping state of graphene layers.



    S. Zhao,b, Rentao Mu, Y. Ninga, Q. Fua and X. Bao
    Applied Surface Science 522 (2020) 146359
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  8. (2020) Human hair, untreated, colored, bleached, and/or treated with a conditioner, by near-ambient pressure x-ray photoelectron spectroscopy

    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 ca. 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Here, we show the NAP-XPS analysis of untreated/blank human hair, and human hair that has been colored (red) and treated with a commercial conditioner, or bleached and treated with a different conditioner. Survey spectra are shown of each material along with figures comparing their Si 2p, S 2p, and C 1s spectra. The survey spectrum of untreated hair shows S 2p, S 2s, C 1s, Ca 2p, N 1s, and O 1s peaks and corresponding O, N, and C Auger signals. The survey spectra of the colored and bleached hair show significant Si 2s and Si 2p signals and reduced or eliminated S 2p and S 2s peaks, presumably due to the deposition of dimethicone (polydimethylsiloxane) from the corresponding commercial hair treatment products. Narrow scans similarly indicate the deposition of a silicon-containing material on the two types of treated hair, with a concomitant decrease in the intensity of the sulfur signals from the hair. Upon treatment, the C 1s envelope also changes—the chemically shifted peak attributable to amide-type carbon disappears.



    V. Jain, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, and M. R. Linford
    Surface Science Spectra 27, 014001, 2020
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  9. (2019) Polytetrafluoroethylene, by near-ambient pressure XPS

    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. Polytetrafluoroethylene (PTFE) is an important polymer with many applications in science and industry. It is an insulator that charges under x-ray illumination at high vacuum. In this submission, we show NAP-XPS spectra of PTFE. Survey spectra are shown at different background gas (air) pressures. These spectra contain F 2s, C 1s, O 1s, N 1s, F 1s, and F Auger signals. Also presented are F 1s narrow scans over a range of background pressures and illumination times. Peaks decrease in width, shift toward literature values, and improve in shape with increasing background gas pressure.



    V. Jain, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014028 (2019)
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  10. (2019) Carbon dioxide gas, CO2(g), by near-ambient pressure XPS

    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 the survey, O 1s, C 1s, valence band, O KLL Auger, and C KLL Auger NAP-XPS spectra of gaseous carbon dioxide, CO2, a material that would be difficult to analyze by conventional XPS. A small N 1s signal from N2(g) is also observed in the survey spectrum. The C 1s and O 1s signals in the narrow scans are fit to Gaussian–Lorentzian sum and asymmetric Lorentzian (LA) functions. Better fits are obtained with the LA synthetic line shape. Since it is likely that CO2(g) will be present in other NAP-XPS analyses, these data should serve as a useful reference for other researchers.



    T. G. Avval, S. Chatterjee, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014022 (2019);
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  11. (2019) Zirconium oxide particles, by near-ambient pressure XPS

    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 ca. 2500 Pa, or even higher in some cases. With NAP-XPS, XPS can probe particles, moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, narrow (Zr 3p, Zr 3d, and O 1s), and Auger (O KLL) NAP-XPS scans of ZrO2 particles. Charge compensation for this insulating sample took place via the residual gas in the chamber. Zirconia is an important ceramic material. Accordingly, the XPS spectra of zirconia should be useful references.



    D. Shah, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 024001 (2019);
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  12. (2019) Poly(L-lactic acid), by near-ambient pressure XPS

    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 2500 Pa or higher. With NAP-XPS, one can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s, and survey NAP-XPS spectra from poly(L-lactic acid). The C 1s and O 1s envelopes were fit with three and two Gaussian-Lorentzian sum functions, respectively. Water vapor (800 Pa) was used as the residual gas for charge compensation, which was confirmed by the sharp peak at 535.0 eV in the O 1s narrow scan. The uniqueness plot corresponding to the C 1s fit shows that the fit parameters had statistical significance. C 1s and O 1s spectra of PLLA damaged by exposure to x-rays for ca. 1 hour are also included.



    D. I. Patel, S. Noack, C. D. Vacogne, H. Schlaad, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 024004 (2019)
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  13. (2019) Liquid water, by near-ambient pressure XPS

    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 ca. 2500 Pa, or higher in some cases. With NAP-XPS, XPS can be used to analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, O 1s, O KLL, and valence band NAP-XPS spectra from liquid water, a material that could not be analyzed at moderate pressures by conventional approaches. The O 1s signal was fit to two components attributed to liquid and vapor phase water. The carbon in the survey spectrum is attributed to contaminants in the water and/or adventitious carbon.



    D. Shah, D. I. Patel, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 024003 (2019)
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  14. (2019) Coca-Cola, by near-ambient pressure XPS

    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 ca. 2500 Pa, or higher in some cases. 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 an NAP-XPS survey spectrum, and also O 1s and C 1s narrow scans, of a commercial soft drink, Coca-Cola. Clearly this is a material that could not be analyzed at moderate pressures by conventional XPS. The C 1s narrow scan is fit to five synthetic components. The O 1s narrow scan shows strong contributions from both liquid and gas phase water. A small N 1s signal in the survey spectrum is attributed to background nitrogen. The shape of the uniqueness plot corresponding to the C 1s fit suggests that the fit parameters are statistically significant.



    D. Shah, C. V. Cushman, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 024005 (2019)
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  15. (2019) Sesame seeds, by near-ambient pressure XPS

    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., greater than ca. 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 NAP-XPS of sesame seeds, a food sample that could not be analyzed at moderate pressures by conventional approaches. Survey spectra from three separate seeds are shown. In addition to the expected C 1s and O 1s signals, seeds show calcium. The C 1s narrow scans from the three seeds are well fit by four components. The largest of these is attributed to carbon singly bonded to oxygen (C—O), which suggests carboydrates or cellulose in the material. A small N 1s peak is observed in all the survey spectra.



    T. Roychowdhury , S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014018 (2019)
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  16. (2019) Dimethyl sulfoxide by near-ambient pressure XPS

    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., 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, O 1s, C 1s, S 2p, and S 2s NAP-XPS spectra from dimethyl sulfoxide (DMSO), a widely used organic solvent that is miscible with water. The sample was analyzed directly in its native, liquid state at room temperature. In general, both liquid and gas phase peaks are observed in the narrow scans. Due to the importance of DMSO in both chemistry and biology, it is likely that it will appear in future NAP-XPS analyses. Accordingly, these data may serve as a reference for future work.



    T. G. Avval, C. V. Cushman, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014020 (2019)
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  17. (2019) Oxygen gas, O2(g), by near-ambient pressure XPS

    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., 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 the survey, O 1s, valence band, and O KLL Auger NAP-XPS spectra of oxygen gas, O2, a material that would be difficult to analyze by conventional XPS. A small N 1s signal from N2(g) is also observed in the survey spectrum. The O 1s narrow scan is fit to Gaussian-Lorentzian sum functions. The Lorentzian character of this synthetic line shape was varied to obtain the best fit. Since it is likely that O2(g) will be present in other NAP-XPS analyses, these data should serve as a useful reference for other researchers.



    T. G. Avval, S. Chatterjee, G. T. Hodges, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014021 (2019)
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  18. (2019) Surface Plasmon Enabling Nitrogen Fixation in Pure Water through a Dissociative Mechanism under Mild Conditions

    Nitrogen fixation in a simulated natural environment (i.e., near ambient pressure, room temperature, pure water and incident light) would provide a desirable approach to future nitrogen conversion. As N≡N triple bond has a thermodynamically high cleavage energy, nitrogen reduction under such mild conditions typically undergoes associative alternating or distal pathways rather than follows a dissociative mechanism. Here we report that surface plasmon can supply sufficient energy to activate N2 through a dissociative mechanism in the presence of water and incident light, as evidenced by in-situ synchrotron radiation-based infrared spectroscopy and near ambient pressure X-ray photoelectron spectroscopy. Theoretical simulation indicates that the electric field enhanced by surface plasmon, together with plasmonic hot electrons and interfacial hybridization, may play a critical role in N≡N dissociation. Specifically, AuRu core-antenna nanostructures with broaden light adsorption cross section and active sites achieve an ammonia production rate of 101.4 μmol·g-1·h-1 without any sacrificial agent at room temperature and 2-atm pressure. This work highlights the significance of
    surface plasmon to activation of inert molecules, serving as a promising platform for developing novel catalytic systems.



    C. Hu, X. Chen, J. Jin, Y. Han, S. Chen, H. Ju, J. Cai, Y. Qiu, C. Gao, C. Wang, Z. Qi, R. Long, L. Song, Z. Liu, Y. Xiong
    J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 30 Apr 2019
    Read more
  19. (2019) XPS studies on dispersed and immobilised carbon nitrides used for dye degradation

    Liquid phase adsorption is a common technique in waste water purification. However, this process has some downsides. The removal of environmentally harmful contaminants from organic liquids by adsorption produces secondary waste which has to be treated afterwards. The treatment can be e.g. high temperatures or a landfill. Photocatalysts such as CN6 can remove the dye under light irradiation but most times they have to be separated afterwards. Immobilisation of these photocatalysts can be one way to address this problem. The resulting photocatalyst layers were analysed in operando by near-ambient pressure XPS. This enabled us to detect the active species, i.e. oxygen radicals, at the surface, responsible for the dye degradation.



    J. Rieß, M. Lublow, S. Anders, M. Tasbihi, A. Acharjya, K. Kailasam, A. Thomas, M. Schwarze, R. Schomäcker
    Photochem. Photobiol. Sci., 2019, Advance Article
    Read more
  20. (2019) Kidney stone, by near-ambient pressure XPS

    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., greater than 2500 Pa. With NAP-XPS, XPS can be used to probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show O 1s, C 1s, and Ca 2p narrow scans and a survey NAP-XPS spectrum from a human urolith, i.e., a kidney stone, which is a biomaterial that could not be analyzed at moderate pressures by conventional approaches.



    T. Roychowdhury, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014017 (2019)
    Read more
  21. (2019) Near ambient pressure X-ray photoelectron spectroscopy monitoring of the surface immobilization cascade on a porous silicon-gold nanoparticle FET biosensor

    Porous silicon (PSi) offers extremely attractive optical, electronic and biofunctional properties for the development of biosensors. In the present work, we have studied the step by step sandwich biofunctionalization cascade of a PSi platform by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and, in parallel, we have developed a three electrode PSi device sensitive to changes in surface conductance. Prior to the NAP-XPS characterization, the organosilanization with glycidyloxy-propyl-trimethoxy-silane, the bioconjugation, and the gold nanoparticle (AuNP) sensitization layer were monitored by spectroscopic ellipsometry. The NAP-XPS analysis revealed outstanding results: a) the NAP-XPS chamber allows detecting the pristine PSi with negligible adventitious carbon contamination, b) the single oxygen bonded carbon component of the Glycidyl group dominates the C1s core level after organosilanization, c) the good progress of the biofunctionalization/recognition is confirmed by the increase of the silica to silicon component ratio in the Si2p core level and, d) the N1s core level describes identical features from the presence of aminoacid sequences in the capture/detection steps. A FET sensing of a prostate specific antigen (PSA) marker was performed through conjugation with AuNPs. For a given concentration of PSA (and AuNPs) the conductance increased with the increase of the gate voltage. For a given gate voltage, the conductance was observed to increase for increasing concentration of PSA. This allowed proposing a calibration line for the biosensor, which is valid from a clinically relevant range of 0.1 ng/mL.



    C. Rodriguez, P. Dietrich, V. Torres-Costa, V. Cebrián, C. Gómez-Abad, A. Díaz, O. Ahumada, M. M. Silván
    Applied Surface Science, Available online 6 June 2019
    Read more
  22. (2019) Introduction to near-ambient pressure x-ray photoelectron spectroscopy characterization of various materials

    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., greater than 2500 Pa. With NAP-XPS, a wide variety of unconventional materials can be analyzed, including moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Charge compensation with NAP-XPS takes place simply through the residual/background gas in the chamber, which is ionized by the incident x-rays. High quality spectra—high resolution and good signal-to-noise ratios—are regularly obtained. This article is an introduction to a series of papers in Surface Science Spectra on the NAP-XPS characterization of a series of materials. The purpose of these articles is to introduce and demonstrate the versatility and usefulness of the technique.



    D. I. Patel, T. Roychowdhury, V. Jain, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 016801 (2019)
    Read more
  23. (2019) Argon gas, by near-ambient pressure XPS

    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., greater than 2500 Pa. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, 2s, 2p, 3s, 3p, and the Auger LMM NAP-XPS spectra from argon gas, a material that could not be analyzed at moderate pressures by conventional methods. A small N 1s signal from residual nitrogen gas in the chamber is also present in the survey spectrum.



    D. I. Patel, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014024 (2019)
    Read more
  24. (2019) Bovine serum albumin, aqueous solution, by near-ambient pressure XPS

    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 (O˭C‒NH2), 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.



    V. Jain, M. Kjærvik, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014027 (2019)
    Read more
  25. (2019) Nitrogen gas (N2), by near-ambient pressure XPS

    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 ca. 2500 Pa, or even higher in some cases. 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 NAP-XPS survey and narrow scans from nitrogen gas (N2), a material that could not be analyzed at moderate pressures by conventional approaches. Nitrogen gas is an important reference material for NAP-XPS because residual N2 from the air and/or venting produces an N 1s signal in many NAP-XPS spectra. Nitrogen gas may also be deliberately employed as the gaseous background for NAP-XPS experiments. The survey spectrum of N2 gas contains N 1s, N 2s, N KLL (Auger), and valence band signals. This submission is part of a series of articles on NAP-XPS that has been submitted to Surface Science Spectra.



    D. Shah, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014023 (2019)
    Read more
  26. (2019) Calcite (CaCO3), by near-ambient pressure XPS

    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 analyze moderately volatile liquids, biological samples, porous materials, minerals, and/or polymeric materials that outgas significantly. In this submission, we show NAP-XPS survey and Ca 2p, O 1s, and C 1s narrow scans from calcite, which was analyzed here without external charge compensation. Quantitation of the peaks in the narrow scan gives a ratio that is very close to the theoretical 1:1:3 ratio expected for Ca:C:O in the material. The small N 1s signal in the survey spectrum is attributed to residual nitrogen gas in the analysis chamber.



    T. Roychowdhury, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014025 (2019)
    Read more
  27. (2019) Water vapor, by near-ambient pressure XPS

    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., greater than 2500 Pa. With NAP-XPS, XPS can be used to probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey and O 1s NAP-XPS spectra from water vapor, a material that could not be analyzed at moderate pressures by conventional approaches and that is expected to be present in many analyses.



    D. I. Patel, D. Shah, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014026 (2019)
    Read more
  28. (2019) Clamshell, by near-ambient pressure XPS

    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 NAP-XPS survey, Ca (3p, 2p, 2s), O 1s, C 1s, and N 1s narrow, and valence band spectra from a clamshell, a material of biological origin that would be challenging to analyze by conventional XPS approaches. Like most shells of biological origin, clamshells are primarily composed of calcium carbonate.



    T. Roychowdhury, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014019 (2019)
    Read more
  29. (2019) Ambient air, by near-ambient pressure XPS

    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 2500 Pa or higher. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Because of the relatively high working pressure of NAP-XPS, the components of ambient air may be present in the analytical chamber during data acquisition. In this submission, we show survey, O 1s, N 1s, valence band, oxygen Auger (KLL), and nitrogen Auger (KLL) NAP-XPS spectra from ambient air, a material that could not be analyzed at moderate pressures by conventional XPS.



    D. I. Patel, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 024002 (2019)
    Read more
  30. (2019) Ethylene glycol, by near-ambient pressure XPS

    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., greater than 2500 Pa. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show C 1s, O 1s, and survey NAP-XPS spectra from ethylene glycol, an organic solvent that could not be analyzed at near-ambient pressures by conventional approaches. An N 1s signal is present in the survey spectrum of the material.



    D. I. Patel, J. O'Tani, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 024007 (2019)
    Read more
  31. (2019) Coffee bean, by near-ambient pressure XPS

    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., up to 2500 Pa, or higher in some cases. NAP-XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we present NAP-XPS C 1s and O 1s narrow scans and a survey spectrum of a coffee bean, a material that would be difficult or even impossible to analyze by conventional XPS. Coffee beans are ground to produce coffee powder, which is the source of one of the world’s most common beverages, coffee. The survey spectrum shows small amounts of sulfur and calcium.



    D. Shah, S. Bahr, P. Dietrich, M. Meyer, A. Thißen and M. R. Linford
    Surface Science Spectra 26, 024006 (2019)
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  32. (2019) Poly(y-benzyl L-glutamate), by near-ambient pressure XPS

    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. In this study, poly(γ-benzyl L-glutamate) (PBLG) with a molar mass of 11.3 kg/mol was analyzed by NAP-XPS; here, we show the survey, C 1s, N 1s, and O 1s narrow scans of PBLG. The C 1s peak envelope was fitted in three different ways, to five, six, or seven synthetic peaks. In each fit, there was also a shake-up signal. The O 1s narrow scan was well fit with three peaks: C—O and C=O in a 1:2 ratio from the polymer, and a higher energy signal from water vapor. Hartree–Fock orbital energies of a model monomer served as a guide to an additional fit of the C 1s envelope.



    V. Jain, J. J. Wheeler, D. H. Ess, S. Noack, C. D. Vacogne, H. Schlaad, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, and M. R. Linford
    Surface Science Spectra 26, 024010 (2019)
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  33. (2019) Catalytic furfural hydrogenation to furfuryl alcohol over Cu/SiO2 catalysts: A comparative study of the preparation methods

    Furfuryl alcohol, a vital intermediate for the production of foundry resins, fragrances, pharmaceuticals and
    pesticide, is produced by hydrogenation of furfural in gas phase or liquid phase. The furfuryl alcohol production
    in gas phase over silica supported copper catalyst is favored thanks to the environmental and technical advantages.
    The effect of preparation methods of silica supported copper catalysts on the structure and performance
    was investigated by means of ICP, N2 physisorption, ex-situ/in-situ XRD, in-situ XPS, FT-IR, H2-TPR, TEM,
    N2O titration, TG as well as furfural hydrogenation. The results indicated that the different catalyst synthesis
    strategies led to the diverse copper species in the calcined samples and disparate Cu0 surface area as well as
    different molar ratio of Cu+/(Cu++Cu0) in the fresh samples. The performance of impregnation derived
    sample was poorer than that of commercial CuCr-Strem catalyst. The catalysts prepared by deposition precipitation
    and ion exchange exhibited similar performance to the CuCr-Strem. The ammonia evaporation derived
    catalyst (Cu/SiO2-EA) showed superior performance in the activity, selectivity and stability among all the studied
    catalysts. The excellent performance was related to the highest surface area of Cu0, smallest copper particle
    size, large surface area and pore volume as well as appropriate higher Cu+/(Cu++Cu0) ratio. Furthermore, all
    the copper catalysts went through deactivation, which was caused by carbon deposition, during the reaction.
    Owing to the largest amount of Cu0 sites and large SBET, the Cu/SiO2-EA exhibited the slowest deactivation rate.



    H. Dua, X. Ma, P. Yana, M. Jianga, Z.Zhaoa and C. Zhang
    Fuel Processing Technology
    Volume 193, October 2019, Pages 221-231
    Read more
  34. (2019) Human tooth, by near-ambient pressure x-ray photoelectron spectroscopy

    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., greater than 2500 Pa. With NAP-XPS, XPS can be used to analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, the authors present the NAP-XPS survey, C 1s, O 1s, Ca 2p, and P 2p narrow scans from a human adult molar tooth, a biological material that would be challenging to analyze by conventional approaches. No pretreatment or cleaning of this dental specimen was performed prior to analysis. Three different regions (top, middle, and root) of the tooth were analyzed. The survey spectra, which differed considerably from each other, show the presence of carbon, oxygen, nitrogen, calcium, and phosphorous. Tin and sulfur are also present in small amounts on the top part of the tooth. C 1s narrow spectra are well fitted with four synthetic peaks.



    D. Shah, T. Roychowdhury, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014016 (2019)
    Read more
  35. (2019) Hard Italian cheese, by near-ambient pressure XPS

    In this submission, we show survey, O 1s, and C 1s near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) spectra from a hard Italian cheese, a material that could not be analyzed by conventional approaches without special sample preparation. The C 1s spectrum is fit under the assumption that the surface of the cheese is primarily fat (triglyceride), which is expected to be the lowest free energy component of the material. The O 1s envelope corresponding to the cheese was well fit to two components of equal area.



    T. Roychowdhury, S. Bahr, P. Dietrich, M. Meyer, A. Thißen, M. R. Linford
    Surface Science Spectra 26, 014015 (2019)
    Read more
  36. (2019) Fretting wear behavior of graphite-like carbon films with bias-graded deposition

    Although graphite-like carbon (GLC) films have been used to protect the engineering components due to their
    high mechanical properties and low friction coefficients, the poor interfacial bonding strength and high internal
    stress can lead their rapid failure. In this study, the bias-gradient (30–120 V) as well as the usual constant bias
    protocols (30, 60 and 120 V) has been adopted to deposit the GLC films on 316 L stainless steel and silicon using
    unbalanced magnetron sputtering technology. Based upon the microstructure and composition analysis by SEM,
    AFM, XRD, Raman and XPS, the sp3 content and compactness of the films are increased with the increase of the
    deposition bias. Compared to the film at the constant bias of 120 V, the bias-graded film has a comparable
    hardness but superior adhesive strength. Detailed fretting wear testing under ambient air and dry N2 atmospheres
    against 25mm diameter Si3N4 ball has been carried out. The friction curves disclosed a three-stage
    evolution feature: the surface working area, the interlayer transition area and the coating failure area. The biasgraded
    film displayed the lowest friction coefficient and the longest fatigue life. Further the fretting mechanisms
    at different stages have been elaborated in terms of the chemical composition, microstructure and mechanical
    properties.



    X. Shi, T. W. Liskiewicz, B. D. Beake, Z. Sun and J.Chen
    Applied Surface Science 494 (2019) 929–940
    Read more
  37. (2019) Bacterial cellulose films with ZnO nanoparticles and propolis extracts: Synergistic antimicrobial effect

    This study aimed to obtain possible materials for future antimicrobial food packaging applications based on biodegradable bacterial cellulose (BC). BC is a fermentation product obtained by Gluconacetobacter xylinum using food or agricultural wastes as substrate. In this work we investigated the synergistic effect of zinc oxide nanoparticles (ZnO NPs) and propolis extracts deposited on BC. ZnO NPs were generated in the presence of ultrasounds directly on the surface of BC films. The BC-ZnO composites were further impregnated with ethanolic propolis extracts (EEP) with different concentrations.The composition of raw propolis and EEP were previously determined by gas-chromatography mass-spectrometry (GC-MS), while the antioxidant activity was evaluated by TEAC (Trolox equivalent antioxidant capacity). The analysis methods performed on BC-ZnO composites such as scanning electron microscopy (SEM), thermo-gravimetrically analysis (TGA), and energy-dispersive X-ray spectroscopy (EDX) proved that ZnO NPs were formed and embedded in the whole structure of BC films. The BC-ZnO-propolis films were characterized by SEM and X-ray photon spectroscopy (XPS) in order to investigate the surface modifications. The antimicrobial synergistic effect of the BC-ZnO-propolis films were evaluated against Escherichia coli, Bacillus subtilis, and Candida albicans. The experimental results revealed that BC-ZnO had no influence on Gram-negative and eukaryotic cells.



    A. Mocanu, G. Isopencu, C. Busuioc, O. M. Popa, P. Dietrich and L. Socaciu-Siebert
    Scientific Reports volume 9, Article number: 17687
    Read more
  38. (2019) Chemical surface analysis on materials and devices under functional conditions – Environmental photoelectron spectroscopy as non-destructive tool for routine characterization

    X-ray photoelectron spectroscopy (XPS) has become a routine analysis method to determine the chemical composition and bonding states of elements of sample surfaces in many industrial applications, like materials development, failure analysis, quality control and device certification. To obtain significant results the analyses of such samples require a fast analysis with reliable quantification and stable data for repeated experiments. In standard XPS experiments under ultrahigh vacuum (UHV) conditions the significance of the results can be affected by changing surface compositions under the analysis conditions, different degrees of degassing and thus changing degrees of differential charging in insulating samples. In this publication the positive influence of XPS analysis under elevated pressures, often named Near-Ambient Pressure XPS or “Environmental XPS” is shown for different samples. Furthermore the process of charge compensation in gas pressures of 1–2 mbar is introduced, followed by a discussion of the perspectives of this “Environmental Charge Compensation”. The paper discusses the efficiency and stability of Environmental Charge Compensations for typical insulating test samples, as well as for different bulk insulators. The additional capability of XPS in elevated pressures is demonstrated on a superabsorbent polymer typically used in diapers, showing the difference of the analysis results for its wet and dry state. The paper ends with the example of a commercial printed circuit board demonstrating the power of the method for routine analysis of complete devices.



    P. Dietrich, S. Bahr, T. Yamamoto, M. Meyer, A. Thissen
    Journal of Electron Spectroscopy and Related Phenomena;
    Volume 231, February 2019, Pages 118-126
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  39. (2018) Design and fabrication of solar light responsive new metal organic frameworks for photocatalysis

    Design and synthesis of multi-dimensional metal organic frameworks has attracted much attention not only due to their intriguing structures and unique properties, but also for their potential applications especially in catalysis. Recently, much effort has been devoted to develop new photocatalyst based on MOFs, motivated largely by a demand for solving pollution problems in view of their potential applications in the green degradation of organic pollutants. MOFs, known as coordination polymers are crystalline materials constructed from metal ions or clusters bridged by organic ligands to form one-, two-, or three-dimensional infinite networks. There are several methods have been applied for synthesis of MOFs particularly solvothermal, hydrothermal, microwave-assisted, electrochemical, mechanochemical and sonochemical synthesis. In this work, new Cadmium and Copper based Metal Organic Framework (MOF) was synthesized under hydrothermal and solvothermal conditions. Its structure was resolved by single crystal X-ray diffraction and further characterized by Powder X-ray diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectra (IR), Thermogravimetric (TGA), UV-Vis, Photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) analysis. The Cd-MOF and Cu-MOF were photocatalytically active for degradation of 2-chlorophenol (2-CP) under solar light irradiation where 69% and 100% of phenol removal was observed respectively. To improve photocatalytic activity of Cd-MOF, different metal ions such as Ag+, Fe3+ and Zn2+ were introduced into the framework through ion-exchange reaction. The UV-Vis results revealed that Fe-Cd-MOF showed an enhanced photoresponse in the visible region, whereas the photoresponse of Ag-Cd-MOF and Zn-Cd-MOF in the ultraviolet light region. Photocatalytic performances of synthesized materials were investigated fordegradation of 2-CP. Among them, Cd-MOF intercalated with Fe3+ exhibited excellent photocatalytic activity compared with Cd-MOF, degrading 92% of 2-CP in 5 hours. It can be attributed to the intercalation of Fe3+, which reduced energy gap of pure MOF, thus increases photocatalytic efficiency.



    N. A. Surib
    Thesis (M.Eng.Sc) - Faculty of Engineering, University of Malaya, 2018
    Read more
  40. (2018) Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS

    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.



    M. Kjærvik, K. Schwibbert, P. Dietrich, A. Thissen, W. E. S. Unger
    Surf Interface Anal. 2018;1–5.
    Read more
  41. (2018) A ligand strategic approach with Cu-MOF for enhanced solar light photocatalysis

    A solar light-active copper-metal organic framework (Cu-MOF) was constructed through a multiple-linker
    strategy employing 1,2,4,5-benzenetetracarboxylic acid (H4btec) and 4,40´ -bis(1-imidazolyl)biphenyl (bimb)
    as ligands. A reaction mixture consisting of ligands and Cu-metal salts was heated to a critical point in a
    hydrothermal reactor. The constructed MOF was studied for materials chemistry through successive
    analytical techniques. The MOF exhibited a planar structure as seen from the topography obtained from
    electron microscopy and substantiated further by crystallographic analyses. Spectroscopic analyses clearly
    revealed its remarkable ability to harvest visible light. Photoluminesce demonstrated the effect of organic
    conjugation over the transition of d–d electrons. Our study clarified the crucial part played by ligand to
    metal charge transfer in charge-carrier generation. The adopted bi-linker approach enhanced the
    photoactivity and prolonged the lifetime of the charge carriers. This was evident in a solar photocatalysis
    experiment through complete removal of 2-chlorophenol in a short period of time. The robust structural
    stability provided by the linkers was established through thermogravimetric analysis, whereas photostability
    was established through successive photocatalytic experiments employing the recovered MOF.



    N.A. Surib, A. Kuila, P. Saravanan, L. C. Simc and K. H. Leong
    NewJ.Chem., 2018, 42, 11124
    Read more
  42. (2017) Detection of suspended nanoparticles with near-ambient pressure x-ray photoelectron spectroscopy

    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.



    M. Kjærvik, A. Hermanns, P. Dietrich, A. Thissen, S. Bahr, B. Ritter, E. Kemnitz, W. E S Unger
    Marit Kjærvik et al 2017 J. Phys.: Condens. Matter 29 474002
    Read more
  43. (2017) Trends in Advanced XPS Instrumentation. 7. Advanced Software Capabilities

    In this article, we focus on the features of a modern XPS software package: the Specslab Prodigy system, which is used in most SPECS instruments. Software packages are an integral part of almost any analytical instrument these days, and purchasing decisions are often based as much on the software of an instrument as its hardware.

    Here, we discuss some of the software innovations that are part of the EnviroESCA. These capabilities make this instrument and other SPECS instruments relatively easy to use and improve their data collection and workup capabilities. Two areas of focus
    here will be the software’s ability to save and allow examination of every individual narrow scan, and its ability to interlace during data acquisition, i.e., alternate between taking different narrow scans and survey scans to avoid taking a block of any one type of scan.



    S. Chatterjee, A. Thißen, P. Dietrich, C. Fleischer, C. V. Cushman, J, Banerjee, N. J. Smith, M. R. Linford,
    Vacuum Technology & Coating, December 2017
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  44. (2017) Trimetalic Heterogeneous Catalyst for Dehydrogenation of Formic Acid with Enhanced CO Tolerance

    Hydrogen energy is considered to be a promising alternative for the sustainable and environmentally friendly solution of the global energy problem. One of the major obstacles of hydrogen energy applications is to maintain safe and efficient storage of hydrogen which can also be achieved chemically using suitable carrier materials. Formic acid (HCOOH, FA) can be utilized as a hydrogen carrier due to its low molecular weight (46 g/mol) and high hydrogen density (%4.4 weight). FA is a stable, non-flammable, and non-toxic biomass side-product rendering it a perfect candidate for an alternative hydrogen vector. Design of novel heterogeneous catalysts which can substitute the existing homogeneous catalytic systems may allow overcoming catalyst isolation and recovery costs and associated logistical problems hindering their applications in on-board operations.

    FA can be catalytically decomposed via dehydrogenation and dehydration reactions. Selective dehydrogenation of FA is crucial because, the production of CO from dehydration mechanism can suppress the activity of the catalyst by blocking/poisoning the precious metal sites. Consequently, development of CO-resistant, selective, catalytically active, and reusable heterogeneous catalysts has a great significance. In the current work, a new material that can produce H2(g) from FA under ambient conditions in the absence of additives with high CO-poisoning tolerance will be introduced, which is comprised of Pd-based trimetallic active centers functionalized with Ag and Cr in addition to amine-functionalized MnOx promoters dispersed on a SiO2 support surface.



    E. Perşembe
    Perşembe, E. (2017). (Unpublished Thesis)
    Bilkent University, Ankara, Turkey.
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  45. (2017) Trends in Advanced XPS Instrumentation. 5. Near-Ambient Pressure XPS

    X-ray photoelectron spectroscopy is the most widely used surface analytical technique, and with good reason. It can quantitatively determine the elemental composition of the outer 5 - 10 nm of a material, and it is sensitive to the oxidation state/chemical environment of the elements it detects. We have described the fundamental operating principles of XPS in previous VT&C articles and other publications. 1-9 XPS has become a fairly mature technique. It was once used almost exclusively by surface scientists. Now it is employed by researchers in many disciplines. XPS has been widely used to characterize semiconductors, ceramics, glass, catalysts, electrochemical devices, biosensors, materials for chromatography, etc.



    C. V. Cushman, C. T. Dahlquist, P. M. Dietrich, S. Bahr, A. Thißen, O. Schaff, J. Banerjee, N. J. Smith, M. R. Linford
    Vacuum Technology & Caoting August 2017, pp. 23-31
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