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NAP-XPS System with SPM and IRRAS

Near Ambient Pressure XPS with SPM and IRRAS Multimethod System for Deeper Surface Analysis

The combination of different analysis techniques allows for getting a deeper insight into the studied processes. Therefore SPECS has designed in which NAP-XPS with SPM and IRRAS allows for the combination of NAP-SPM or FTIR spectroscopy for deeper insight into the surface processes .

NAP-SPM technique is an excellent complementary tool to NAP-XPS. While NAP-XPS delivers information about the chemical composition of the sample surface, NAP-SPM  allows the user to get atomically resolved images of the studied surfaces under UHV conditions or in a specific gas atmosphere.

The SPM Aarhus NAP is perfectly suited to be incorporated into complex multimethod systems. Due to its excellent mechanical stability the SPM Aarhus NAP can deliver atomic resolution even when different system modules are in full operation. The below image shows an example of a system where the SPM Aarhus NAP is combined with a NAP-XPS and a preparation system module.

IR-spectroscopy is an established method for measuring the vibrational signature of a molecule. It can distinguish between molecules in the gas phase and adsorbed molecules on a surface on different sites. Therefore, IRRAS technique is extremely well suited for investigations of surfaces under a specific gas atmosphere and a widely-used complementary investigation method to NAP-XPS. Examples of NAP-XPS systems combined with IRRAS are shown in the pictures below.

KEY FEATURES

  • NAP-SPM / NAP-XPS system equipped with Aarhus SPM NAP for surface science studies in controlled atmospheres of pressures of up to 100 mbar
  • Ideal for combination with complementary techniques due to the outstanding stability of the Aarhus SPM
  • NAP-XPS / IRRAS system equipped with FTIR spectrometer suitable for IR-spectroscopy under UHV as well as specific gas atmospheres
  • Optional polarization module for PM-IRRAS
  • Customizable gas handling system
  • Modular system concept allows for efficient upgrade options (sample preparation module, HPC 20, etc.)
  • Well established and proven performance with a large installed base worldwide

MADE FOR THESE METHODS

4

PUBLICATIONS

  1. (2020) In situ work-function measurement during chemical transformation of MoS2 to MoO3 by ambient-pressure x-ray photoelectron spectroscopy

    In this study, the oxidation of a two-dimensional (2D) MoS2 was performed as an alternative route
    for the synthesis of a 2D-layered MoO3 structure with high work function (WF) and hole mobility.
    The proposed method can also be used to tune the electronic properties (WF and bandgap) of MoO3/
    MoS2 composite-based semiconductors. By ambient pressure x-ray photoelectron spectroscopy
    (AP-XPS), in situ monitoring of the WF and chemical state of the surface was carried out during
    the oxidation of MoS2 to MoO3 layers. By heating the MoS2 sample in an O2 + Ar gas environment,
    the chemical transformation of the MoS2 to a MoO3/MoS2 composite layer and eventually to MoO3
    was observed. The chemically transformed MoO3 film had a properly layered structure, according
    to cross-sectional transmission electron microscopy and high-resolution grazing-incidence x-ray
    diffraction analyses. During the oxidation, the WF change according to the change in surface
    chemical state was simultaneously measured using Ar gas as a surface potential probe. This study
    demonstrates the capability of AP-XPS for the monitoring and optimization of the conditions for
    chemical transformation (oxidation) to achieve desired physical properties (e.g. WF).



    D. Lee, J. H. Jang, W.Song, J. Moon, Y. Kim, J. Lee,
    B. Jeong, and S. Park
    2D Mater. 7 (2020) 025014
    Read more
  2. (2020) AP-XPS beamline, a platform for operando science at Pohang Accelerator Laboratory

    Beamline 8A (BL 8A) is an undulator-based soft X-ray beamline at Pohang
    Accelerator Laboratory. This beamline is aimed at high-resolution ambientpressure
    X-ray photoelectron spectroscopy (AP-XPS), soft X-ray absorption
    spectroscopy (soft-XAS) and scanning photoemission microscopy (SPEM)
    experiments. BL 8A has two branches, 8A1 SPEM and 8A2 AP-XPS, that share
    a plane undulator, the first mirror (M1) and the monochromator. The photon
    beam is switched between the two branches by changing the refocusing mirrors
    after the monochromator. The acceptance angle of M1 is kept glancing at 1.2o,
    and Pt is coated onto the mirrors to achieve high reflectance, which ensures a
    wide photon energy range (100–2000 eV) with high resolution at a photon flux
    of ~1013 photons s-1. In this article, the main properties and performance of the
    beamline are reported, together with selected experiments performed on the
    new beamline and experimental system.



    G. Kim, Y. Yu, H. Lim, B.Jeong, J. Lee, J. Baik, B. S. Muna and K.-J. Kim
    J. Synchrotron Rad. (2020). 27, 507–514
    Read more
  3. (2019) Ionic-Activated Chemiresistive Gas Sensors for Room-Temperature Operation

    The development of high performance gas sensors that operate at room temperature
    has attracted considerable attention. Unfortunately, the conventional
    mechanism of chemiresistive sensors is restricted at room temperature by
    insufficient reaction energy with target molecules. Herein, novel strategy for
    room temperature gas sensors is reported using an ionic-activated sensing
    mechanism. The investigation reveals that a hydroxide layer is developed by
    the applied voltages on the SnO2 surface in the presence of humidity, leading
    to increased electrical conductivity. Surprisingly, the experimental results
    indicate ideal sensing behavior at room temperature for NO2 detection with
    sub-parts-per-trillion (132.3 ppt) detection and fast recovery (25.7 s) to 5 ppm
    NO2 under humid conditions. The ionic-activated sensing mechanism is
    proposed as a cascade process involving the formation of ionic conduction,
    reaction with a target gas, and demonstrates the novelty of the approach. It
    is believed that the results presented will open new pathways as a promising
    method for room temperature gas sensors.



    Y. G. Song, Y.-S. Shim, J. M. Suh, M.-S. Noh, G. S. Kim,
    K. S. Choi, B. Jeong, S. Kim, H. W. Jang, B.-K. Ju,
    and C.-Y. Kang
    Small 2019, 15, 1902065
    Read more
  4. (2019) Propane dehydrogenation over vanadium-doped zirconium oxide catalysts

    Bulk ZrO2 is a highly active and selective catalyst for dehydrogenation of propane (PDH), in which coordinatively
    unsaturated Zr cations (Zrcus4+) serve as active sites. Substitution of dopant ions into Zr lattice can improve its catalytic activity by generating more Zrcus4+ sites. In this work, a series of vanadium-doped ZrO2 metal oxides (VZrO-x) have been prepared and the influences of vanadium content on their properties have been systematically investigated. Various characterization techniques showed that an appropriate amount of vanadium dopant helps more Zrcus4+ sites to be created by a structural transformation and H2 pretreatment. However, excess vanadium dopant led to a negative effect on the catalytic activity owing to the formation of
    bulk-like V2O5 crystallites. The catalytic activity of VZrO-x is well correlated with the amount of Lewis acid sites
    because Zrcus4+ cations correspond to Lewis acid sites. The VZrO-8 catalyst exhibited two times higher activity
    than pure ZrO2. Moreover, for repeated cycles the activity was totally recovered by oxidative regeneration
    followed by reductive pretreatment. Finally, the performance test results showed that H2 co-feeding can further
    enhance the activity by suppressing coke deposition during PDH.



    N. Jeon, H. Choe, B.Jeong, and Y. Yun
    Catalysis Today
    Read more
  5. (2019) Cu-promoted zirconia catalysts for non-oxidative propane dehydrogenation

    Bulk ZrO2 has shown high activity and selectivity for propane dehydrogenation (PDH). Its catalytic performance
    can be enhanced by substitution of the Zr ions with suitable dopant ions. In this study, a series of Cu-doped ZrO2
    metal oxides (CuZrO-x) have been prepared using the co-precipitation method and the effects of the amount of
    dopant on their properties have been investigated. The appropriate amount of Cu dopant promotes the creation
    of oxygen vacancies and coordinatively unsaturated Zrcus4+ sites, active sites for PDH; however, excess Cu forms
    bulk CuO in the CuZrO-x catalysts resulting in decreased activity. The catalytic activity for PDH is closely
    correlated to the amount of weak Lewis acid sites in CuZrO-x. Moreover, a comparison of the CuZrO-x properties
    with those of Cu-impregnated ZrO2 has shown that the amount of acid sites and therefore, the catalytic performance,
    depends on the doping method.



    N. Jeon, H. Choe, B.Jeong, and Y. Yun
    Applied Catalysis A, General 586 (2019) 117211
    Read more

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