Near Ambient Pressure XPS (NAPXPS)

Allows for characterisation of materials under realistic reaction conditions


XPS has, for many years been used study surfaces, being routinely used in areas such as catalysis, corrosion, and electrochemistry, where the chemical nature of the surface is critical.


However, most of the analysis is made of fresh or spent materials, that is to say a pre- or post-mortem analysis of a material, therefore only observing state of the sample before and after a chemical reaction has occurred. NAP-XPS represents a revolution in the field, allowing for XPS characterisation of a sample in a gaseous environment.


Analysis is achieved by containing the sample in a high-pressure cell which is open to the analyser via a small aperture. A series of pumping stages after this aperture quickly reduce the pressure back down to high vacuum and limits the distance the electrons have to travel through a high pressure of gas. By placing the surface of the sample very close to this aperture, the area under analysis can be in a high pressure of gas while also allowing a usable fraction of the emitted photoelectrons to escape and reach the detector.




NAP-XPS is useful in understanding:

  • surface chemistry changes during analysis of samples in the presence of a gas (or mixture of gases) up to a total pressure of 25 mbar.
  • studying the interaction and effect of water and other liquids with surfaces.
  • determination of intermediate species.

Our partners at Manchester Univrsity offer access to a SPECS NAP-XPS system for such measurements.

  • Available gases: CO2, H2O, O2, H2, CO, NH3. Other gases may be possible by request.
  • Heating/cooling of samples from ~ 0ºC to 700ºC during analysis.