Ultra-High Vacuum (UHV)-Preparation line
An ultra-high vacuum (UHV) “backbone” has been established, which allows fast (<4 minutes), automated transfer of samples between large-scale, industry-relevant deposition clusters and an experimental endstation that is connected to the BESSY II storage ring via a “two-color” beamline.
Currently, the main available experimental technique is soft/hard x-ray photoemission spectroscopy, based on the endstation equipped with a Scienta EW4000 hemispherical analyzer. The wide variation in available excitation energy allows a correspondingly wide variation in the probing depth of the technique (on the order of 0.5 nm to 15 nm in a given material) allowing a detailed, non-destructive depth-profile of the chemical and electronic properties to be obtained in a single experiment.
A great deal of information regarding the nature of electronic orbitals in valence bands can also be extracted, based on the changing photoionization cross section (and therefore measured intensity) of orbitals with changing excitation energy. Changes in the shape of measured valence band spectra can therefore be related to relative contributions of different orbitals to hybridized states. Other phenomena, such as the energy-dependence of recoil effects, can be best understood and exploited using such measurements.