What is APXPS?
APXPS (Ambient or Near Atmospheric Pressure XPS) allows for surface analysis at pressures several orders of magnitude higher than those in UHV systems — often in the millibar to near-atmospheric range. This capability bridges the gap between fundamental surface science and realistic operating environments, enabling researchers to study materials as they truly behave under working conditions.
Understanding Surfaces Under Real Conditions
When surfaces are analysed at higher pressures, their structure and chemistry can differ significantly from what is observed under UHV. Adsorbed gases, reaction intermediates, and dynamic chemical changes can alter surface composition and electronic states. These effects are particularly important in catalysis, corrosion, energy conversion, and environmental chemistry, where interactions with gas-phase species define material performance.
By enabling XPS analysis in the presence of gases such as O₂, H₂, CO, CO₂, or water vapour, APXPS opens a window into dynamic surface processes that cannot be captured in traditional vacuum-based studies.
Correlating XPS and Mass Spectrometry Data
To gain deeper insight into gas–surface interactions, APXPS systems can be coupled with a Hiden Analytical mass spectrometer. This combination provides real-time gas phase analysis, allowing users to correlate surface chemistry (from XPS) with gas composition and reaction products (from mass spectrometry).
This powerful pairing helps researchers track how gas reactions influence surface states, and vice versa — offering a complete picture of catalytic mechanisms, adsorption behaviour, and reaction kinetics under near-operational conditions.
Applications and Advantages:
- Operando spectroscopy in catalysis – A spectroscopic tool that enable the characterization of a working catalyst (XPS) with the simultaneous evaluation of its catalytic performance (MS)
- Corrosion and oxidation studies in near-atmospheres: Understanding how a coating or alloy surface evolves in a gas environment (e.g., O₂, H₂O vapour) is key. A Hiden system allows you to track gas phase species (e.g., evolved H₂, CO₂) while the XPS characterises the surface chemistry as it develops.
- Thin‐film processing, plasma or vacuum‐to‐atmosphere transitions: Surfaces processed under vacuum and then exposed to gases may change structure or composition. APXPS allows surface analysis in these nearer-real conditions while simultaneously monitoring the gas phase composition with the Hiden mass spectrometer.
Bridging the Gap Between Surface Science and Application
By moving XPS out of the constraints of UHV and into more realistic environments, APXPS enables true in situ and operando surface analysis. Researchers can now observe materials in action — capturing transient phenomena and understanding how real-world conditions shape surface chemistry.
