COMPACT GRATING SPECTROMETER FOR INVERSE PHOTOEMISSION SPECTROSCOPY

We report on a normal incidence grating spectrometer for angle-resolved inverse photoemission spectroscopy covering a photon energy range from 10 to 40 eV. Following diffraction from a spherical grating with 201.4 mm radius and 3600 lines/mm the photons are recorded by a position sensitive detector. The compact mounting of the grating and detector on a single 150 mm CF flange is established by displacing detector and sample from the Rowland circle. The performance of the spectrometer concerning energy calibration, spectral efficiency, optical resolution, and count rates was experimentally investigated and found to match the design goals well. Operated together with a low energy electron gun using a low temperature BaO cathode a typical total energy resolution of 360 meV at hν=15 eV is obtained in inverse photoemission spectroscopy. It is shown that due to its compactness the spectrometer unit can be effectively combined with other components for surface analysis.