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We present a spectrometer for inverse photoemission in the VUV range with variable energy resolution between 400 and 165 meV FWHM (full width at half maximum). The energy distribution of the electron beam used for excitation can be adjusted between 300 and 125 meV by the use of a toroidal 90 o electrostatic deflector combined with a slit aperture. The emitted photons are detected by Geiger-Müller counters filled with either acetone or iodine as counting gas. The optical bandpasses of the detectors can be tuned between 100 and 330 meV by varying the temperature of their entrance windows. The overall resolution of the spectrometer is determined by measuring the Fermi-level onset in inverse-photoemission data of polycrystalline gold. Furthermore, the resolution enhancement is demonstrated by spectra of image-potential-induced surface states at Cu(001).

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