Resonant double-core excitations with ultrafast, intense X-ray pulses

Intense few-to-sub-femtosecond soft x-ray pulses can produce neutral, two-site excited double-core-hole states by promoting two core electrons to the same unoccupied molecular orbital. We theoretically investigate double nitrogen K-edge excitations of nitrous oxide (N2O) with multiconfigurational electronic structure calculations. show that second core-excitation energy is reduced respect its ground state value. A site-selective mechanism using intense few-femtosecond x-rays investigated time-dependent Schrodinger equation (TDSE) simulations. The subsequent two-step Auger-Meitner and two-electrons-one-electron decay spectra core-excited are analyzed a Mulliken population analysis multiconfirational wavefunctions. change in electron emission lineshape between absorption 1 or 2 photons resonant predicted combining this approach TDSE examine possibility resolving pump-probe techniques calculating chemical shifts core-electron binding products.