Status and perspectives of high-resolution spectroscopy in the soft x-ray range (invited)

Abstract

The present status in high-resolution photoabsorption and photoemission spectroscopy using synchrotron radiation in the soft x-ray range (40 eV≤hν≤1000 eV) is described. With the SX700/II monochromator, operated by the Freie Universität Berlin at the Berliner Elektronenspeicherring für Synchrotronstrahlung (BESSY), a resolving power of up to ≥10 000 has been achieved. A practical feature of this monochromator is given by the fact that excellent energy resolution is achieved with a single 1221-lines/mm grating in the whole soft x-ray range considered. This opens up new opportunities in core-level photoabsorption spectroscopy of atoms, molecules, adsorbed species, and solids. A combination of the SX700/II beam line with a high-resolution electron spectrometer (ΔE≂15 meV) enables resonant photoemission studies of rare-earth materials in the 4d→4f giant-resonance region with unprecedented resolution and also at the 3d→4f absorption thresholds. This spectroscopic progress provides new insight into the correlated electronic structure of Ce systems.