Study of the competition between relaxation and core-hole decay by Auger-photoelectron coincidence spectroscopy

When an incompletely relaxed core-hole state can relax further to a fully relaxed one on the time scale of core-hole decay, the photoelectron line of the incompletely relaxed state is observed in coincidence with the singles Auger-electron line by the decay of the fully relaxed core-hole state. With an increase in the relaxation rate from the incompletely relaxed core-hole state to the fully relaxed one, the relative intensity of the incompletely relaxed core-hole state which relaxes further to the fully relaxed core-hole state on the time scale of core-hole decay increases in both the coincidence photoelectron main line and the singles one. At the same time, the ratio of the Auger-electron line intensity by the decay of the fully relaxed core-hole state to that by the decay of the incompletely relaxed core-hole state in the Auger-electron spectrum measured in coincidence with the singles photoelectron line of the incompletely relaxed core-hole state increases. When the imaginary part of the initial core-hole self-energy is considerably energy dependent, the photoelectron (or Auger-electron) line measured in coincidence with the singles Auger-electron (or photoelectron) line peak does not necessarily coincide with the singles one. The energy shift between the two line peaks increases with the relaxation rate.