A new photon counter for inverse photoemission

Data are presented obtained from a new design of high‐resolution (70 meV) and high‐sensitivity, fixed isochromat detector for use in inverse photoemission whose peak quantum efficiency is 20% at an energy of 10.08 eV. The detector design is of the Geiger type with a novel combination of a CaF2 window and CS2 vapor fill. The performance of this detector is compared with others currently being used. It is suggested that this design could provide an inexpensive viable alternative for high‐resolution spectroscopy systems. Inverse photoemission spectra obtained from a CuNi(111) surface in ultrahigh vacuum are presented.