Near ambient pressure X-ray photoelectron spectroscopy
In addition to a conventional XPS spectrometer, ISAS is operating one of the few laboratory near ambient pressure (NAP) XPS-spectrometers existing worldwide.
The elemental surface composition and its spatial distribution, the quantities of the elements, the surface contamination, and the chemical state of the elements are the most important data obtained from the primary information in XPS-spectra, the core electron binding energies. NAP-XPS extends the potential of XPS analysis by making it possible to measure spectra under pressure conditions up to ~5 mbar, in contrast to the ultrahigh vacuum (UHV) conditions required for conventional XPS. Due to a differential pumping system and a special geometry of the apparatus, it is possible to measure gases and liquids with NAP-XPS in addition to solid samples.
Our main focus is on the investigation of corrosion, of catalytic reactions at surfaces, and of environmental and biological systems under nearly native conditions. One example of our studies is the characterization of the affinity between phosphopeptides and titania, a problem from proteomic chromatography. A thin liquid film at the titania surface serves as an important “link” between both substances and enables the peptides to unfold. We aspire to realize a characterization of the surface with NAP-XPS under the same conditions as in the underlying chromatographic application.