XPS imaging is a technique which enables the collection of a 2D surface chemical map (or even a 3D map in combination with a technique such a ion bombardment).
There are two types of acquisition. The first is a rastering mode in which a focused beam creates a snapshot analysis of a region (usually around 10 eV window) and the sample stage moves incrementally, recording individual spectra at each co-ordinate (such as with the microfocused X-ray beam on the Thermo NEXSA system at HarwellXPS Hub).
The second type of imaging is known as parallel imaging and involves a spread beam setting a 2D detector to a single energy and opening the analysis area to collect electron counts at every co-ordinate in the analysis area simultaneously. This configuration may be found on systems with a collimation/lens configuration like that of the Kratos SUPRA (available at the HarwellXPS hub). This allows a faster image to be taken but only at a singular energy.
Either method may be repackaged into the same format by CasaXPS eventually (provided correct experimental procedure is followed), so which method to choose will likely depend on whether or not a full snapshot spectra is needed or even just which instrument the user is more comfortable with or has access to.
CasaXPS analysis of rastered imaging data may be followed in the video below.
- Cushman C., et al. (2017) Trends in Advanced XPS Instrumentation. 3. The spherical mirror analyzer: obtaining spatially resolved XPS data without rastering. Vacuum Technology & Coating. Read it online here.