We observe formation of two core holes in a single-photon transition , each hole at a different carbon atom of the C2H2 molecule. At a photon energy of 770.5 eV, the probability of this 2-site core double ionization amounts to 1.6±0.4% of the 1-site core double ionization. A simple theoretical model based on the knockout mechanism gives reasonable agreement with experiment. Spectroscopy and Auger decays of the associated double core hole states are also investigated. Energy shifts of these states are larger than for single core states. An improved chemical sensitivity may be of a potential use for future analytical methods.
COBISS.SI-ID: 25430823
Experimental evidence for the correlated two-electron one-photon transitions (1s-2 -) 2s-1 2p-1) following single-photon K-shell double ionization is reported. The double K-shell vacancy states in solid Mg, Al, and Si were produced by means of monochromatized synchrotron radiation, and the two-electron one-photon radiative transitions were observed by using a wavelength dispersive spectrometer. The two-electron one-photon transition energies and branching ratios of the radiative one-electron to two-electron transitions were determined and compared to available perturbation theory predictions and configuration interaction calculations.
COBISS.SI-ID: 24932647
Atomic x-ray absorption of cadmium in the energy region of L edges was measured on the vapor of the element, in parallel with the absorption of Cd metal foil. Ionization thresholds of the three subshells are determined from the edge profiles, through the energies of pre-edge resonances and indium optical levels in the Z + 1 approximation. A purely experimental result, without extraneous data and with an accuracy of 0.2 eV, is the energy difference between the pre-edge resonance and the threshold energy of the metallic state. Some multielectron-excitation resonances are identified within 30 eV above the edges. The metal foil absorption is used for absolute determination of Cd absorption coefficient.
COBISS.SI-ID: 2375012