Double core-hole spectroscopy
Cederbaum et al. found that the molecular double core-hole (DCH) states probes the chemical environment more sensitively than the single core-hole (SCH) states. [JCP 1986] There are two types of double core-holes: two-site DCH (tsDCH) state is more sensitive to the chemical environment than SCH state, while the single-site DCH (ssDCH) state shows similar chemical shift to SCH state. Recent development of x-ray free-electron laser (FEL) and multi-electron coincidence spectroscopy has realized the observation of these DCH states.
We recently proposed that the relaxation energy and inter-atomic relaxation energy can be extracted from the observation of these ssDCH and tsDCH states, respectively. [JCP 2010, CPL 2010, PRL 2010, 2011, PNAS 2011] We also investigated the sequential Auger decay from the DCH states to CVV (triply charged) and VVVV (quadruply charged) states. [JCP 2011]