Calculation of X-ray emission from doubly ionized neon

When an X-ray source with extremely high brilliance such as an X-ray free electron laser is used for X-ray spectroscopy experiments, we have to consider the significant population of the two core-hole states because of two-photon x-ray absorption (see, for example, the previous news article, ""Hollow" neon atom created by X-ray laser excitation" in X-ray Spectrometry, Vol. 39, No.5 (2010)). A research group led by Professor F. Gel'mukhanov (Royal Institute of Technology, Sweden) has recently published the calculation of the resonant X-ray emission from a neon atom induced by the two-photon population of a double-core-hole excited state. They studied mainly 2 cases; an off-resonant intermediate single-core-hole state, and a resonant core-ionized intermediate state. For more information, see the paper, "Two-photon-induced x-ray emission in neon atoms", Y-P. Sun et al., Phys. Rev. A 82, 043430 (2010).