COMPACT GRATING SPECTROMETER FOR INVERSE-PHOTOEMISSION SPECTROSCOPY

We report on a normal incidence grating spectrometer for angle-resolve d inverse photoemission spectroscopy covering a photon energy range fr om 10 to 40 eV. Following diffraction from a spherical grating with 20 1.4 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 c oncerning energy calibration, spectral efficiency, optical resolution, and count rates was experimentally investigated and found to match th e 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 hv=15 eV is obtained in inverse photoemission spectrosco py. It is shown that due to its compactness the spectrometer unit can be effectively combined with other components for surface analysis. (C ) 1997 American Institute of Physics.