K-ABSORPTION SPECTRA OF ATOMIC CA, CR, MN AND CU

The Is x-ray absorption spectra of atomic calcium, chromium, manganese and copper were determined experimentally and calculated theoretically. The spectra are dominated by a prominent line at threshold which precedes a smooth continuum extending to higher energies. Hartree-Fock calculations taking relativistic effects, relaxation and term dependence into account describe the discrete atomic resonance at threshold very well. The resonances at threshold have no counterpart in the spectra of the metals. The experimental atom to metal core level binding-energy shifts agree well with the predictions of the thermodynamical model by Johansson and Martensson.