CAT

CAT@EMIL

Ambient pressure - High Energy XPS (AP-HE-XPS)

The instrument is part of the Energy Materials in-situ laboratory EMIL, which is a unique infrastructure designed to allow for in-system, in-situ, and operando X-ray analysis of an unprecedented range of materials and devices for energy conversion and storage. The scientific aim at CAT@EMIL is to study the electronic surface/near surface structure of functional materials in the presence of a reactive environment. This includes both gas/solid interfaces (e.g. heterogeneous catalysis) and liquid/solid interfaces (e.g. catalytic water splitting).

The EMIL beamline has two branches – soft (80 eV – 1800 eV) and tender (1800 eV – 10 keV) x-rays – which converge at the CAT instrument.

Selected Applications:
  • X-ray photoelectron spectroscopy (XPS) under high vacuum (p=10-10 Pa) and ambient pressure conditions (typically p=100 Pa)
  • X-ray aborption spectroscopy (XAS) at pressure up to 1kPa (up to 1MPa with reaction cell) in NAP-HE-XPS endstation.
Fig. 1: Sketch demonstrating the main components of the AP-HE-XPS (left). Photo of the complete AP-HE-XPS endstation (right, courtesy of Specs GmbH, Berlin)

Fig. 1: Sketch demonstrating the main components of the AP-HE-XPS (left). Photo of the complete AP-HE-XPS endstation (right, courtesy of Specs GmbH, Berlin)


Methods

HAXPES, NAP-XPS, XPS, EXAFS, NEXAFS, Time-resolved absorption, Mass Spectrometry

Remote access

not possible

Instrument data
Phone (~49 30 8062-) 12109
Beam availability 12h/d
Source
  • UE48
  • CMPU17
    • Monochromator
  • UE48: PGM 400 l/mm and 800 l/mm (both blazed)
  • CPMU17: PGM 400 l/mm, 800 l/mm; DCM Si(111), Si(311), Si(422)
    • Energy range (at experiment)
  • UE48: 80 eV to 2000 eV
  • CPMU17: PGM: 700-1600 eV // DCM: 2200-10000 eV
    • Energy resolution
  • UE48: E/ΔE ~ 1000 (@2000 eV) - 10000 (@80 eV)
  • CPMU17: PGM: E/ΔE ~ 2000 // DCM: E/ΔE ~ 10000 (Si111)
    • Flux
  • UE48: 1012 - 1013 ph/s
  • CPMU17: PGM: 1013 ph/s // DCM: 1011-1012 ph/s
    • Polarisation
  • UE48: horizontal, vertical, circular
  • CPMU17: horizontal
    • Focus size (hor. x vert.)
  • UE48: 140 x 48 µm²
  • CPMU17: 150 x 20 µm² (DCM); 180 x 50 µm² (PGM)
    • Temperature range 25 - 800 °C
    Pressure range 10-8 - 20 mbar; typically 1 mbar
    Detector 2D CMOS detector (SPECS)
    Manipulators various, exchangeable for optimised sample environments
    Sample holder compatibility Homemade concept. For details contact the station manager.
    Additional equipment gas analytics
    • electron impact mass spectrometer (differentially pumped)
    • proton-transfer-reaction mass spectrometer (PTR-MS)
    • TRACE 1310 gas chromatograph
    Additional information Details beamline UE48 and CPMU17
    Fig. 2: Photo of the main components of the reaction cell

    Fig. 2: Photo of the main components of the reaction cell

    Table. 1: Gas analytics

    Table. 1: Gas analytics


    Obviously, the understanding of the interaction of a catalyst surface with the reactants plays a key role in a detailed description of catalytic processes. X-ray photoelectron spectroscopy (XPS) is a well-established powerful tool to study in detail the outermost surface of solids but it was traditionally restricted to high vacuum and low pressure conditions. However, recently a methodology based on a differentially pumped electrostatic lens system has gained much interest. Such an instrument is operated by the Max Planck Institute for Chemical Energy Conversion (MPI-CEC) and the Fritz-Haber-Institut der MPG (FHI-MPG) at HZB/BESSY II at the ISISS beamline in the low photon energy range. A further developed set-up is installed at CAT@EMIL. The feasibility to investigate buried layers is added by the extension of the kinetic energy range of photo-electrons to up to 7000eV. A very flexible, modular sample environment has been developed that allows to apply AP-XPS to a huge variety of problems.

    A sketch of the main components of the AP-HE-XPS instrument and a photo of the complete set-up (courtesy of SPECS GmbH, Berlin) is shown as Fig. 1.

    Variable pressure soft X-ray absorption (vP-XAS)

    A variable pressure soft X-ray absorption cell has been constructed by FHI that works in the conversion electron yield detection and total fluorescence yield mode. This reaction cell allows to measure surface sensitive X-ray absorption spectra in a pressure range between 102 - 105 Pa, i.e. up to atmospheric pressure at temperatures up to 400ºC. This low volume reaction cell makes it feasible to study heterogeneous catalytic reactions in a broad pressure range and hence allows to link results obtained with AP-XPS and measurments obtained in a catalytic reactor.

    A photo of the main components of the reaction cell is shown in Fig. 2.