Photoelectron Spectroscopy

Since decades the Photoelectron Spectroscopy (XPS – X-ray Photoelectron Spectroscopy) is one of standard methods in surface science and is based on the photoelectric effect1. Photons are absorbed by an atom at or near the surface which then emits an electron. The energy of this electron is characteristic for the emitting atom and its chemical state. In recent years, the method has evolved from pure application under ultra-high vacuum conditions to near ambient pressures.

A Near Ambient Pressure in-situ Photoelectron Spectrometer (NAP-XPS – Near Ambient Pressure X­ray Photoelectron Spectroscopy) for the investigation of catalyst materials will be available at the LIKAT at the end of 2019 and is funded by the state of Mecklenburg-Western Pomerania by European Union funds from the European Regional Development Fund (funding period 2014-2020). The new device enables XPS analysis under more realistic reaction conditions up to pressures of 25mbar and temperatures of up to 1000°C. In this way, changes in the surface compositions or oxidations state of elements can be tracked in-situ. The detection of reaction products is carried out by a mass spectrometer coupled directly to the energy analyzer.

The NAP-XPS from SPECS GmbH is currently in production and delivery and commissioning is scheduled for the end of 2019.

We currently have an ultra-high vacuum spectrometer with the following equipment:

VG ESCALAB 220 iXL (VG Scientific) with

  • monochromatic Al Kα X-ray anode and TWIN anode (Mg Kα and Al Kα radiation) for X-ray photoelectron spectroscopy (XPS)
  • gas discharge light source for UV photoelectron spectroscopy (UPS) 
  • ion source for sputtering 

In the load lock of the analytical chamber a gas cell is available which allows a pre-treatment of the sample with various gases at temperatures up to 450°C and a subsequent transfer to the analysis chamber without air contact.
  

 

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[1] The photoelectric effect was explained by Albert Einstein in 1905. Therefor Einstein received the Nobel Prize in Physics in 1921. Already in 1919 the University of Rostock awarded Einstein an honorary doctorate for his work.