Applied NAP-XPS on Sensitive Materials

Photoelectron spectroscopy (XPS) is used to study the elemental composition and to describe the corresponding electron configuration in a sample surface. The application of near-ambient pressure (NAP) conditions to sensitive surfaces can help to avoid structural changes induced by high vacuum or highly energetic radiation exposure. Besides the charming effect that the utilized gases and gas mixtures are considered as known standards for binding energy referencing, they are also being used to compensate unwanted surface charging and eventually participate in a surface reaction to modify the sample surface in-situ. Catalytically active powders, non-conductive support materials, porous materials for adsorption studies and thin electrolysis or fuel cell membranes are challenging subjects of investigation with NAP-XPS when an investigation with conventional XPS is limited. An optimized measurement setup is achieved by diligent sample preparation on suitable sample carriers and by applying appropriate measurement settings, such as pass energy variation, mixing of gases and applying adequate gas pressure for suitable referencing and calibration. The data received with an EnviroESCA system is carefully evaluated using CasaXPS software.