Design and performance of a high-resolution electron energy analyser for angle-resolved photoemission spectroscopy

The design and performance of a solid-state angle-resolved photoemission (ARP) spectrometer is described. The electron energy analyser is based on a 180 degrees hemispherical electrostatic deflector, the design being optimised for energy resolution and sensitivity. Using He I (h nu =21.2 eV) excited ARP spectra of the Cu(001) M Tamm state, the empirically determined energy resolution is found to approach the theoretical limit. With the current choice of defining apertures the theoretical limit (for the Tamm state) is 14 meV, and the angular resolution is +or-2 degrees . The observation of previously unresolved thermal effects on the intensity, inverse lifetime and binding energy of the Tamm state feature illustrates a typical application of the instrument.