Remaining problems in the combined XPS/UPS/FES system

The study aims to investigate the energy band diagram of emitting diamond using the electron energy distribution obtained from combined X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and field emission spectroscopy. Combination of UPS and FES can determine the origin of electron field emission relative to the electronic structure of diamond. By adding XPS, the origin of field-emitted electrons can further be related to the surface termination, which is known to greatly affect the emission properties.