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 theoreticall y. The spectra are dominated by a prominent line at threshold which pr ecedes a smooth continuum extending to higher energies. Hartree-Fock c alculations taking relativistic effects, relaxation and term dependenc e into account describe the discrete atomic resonance at threshold ver y well. The resonances at threshold have no counterpart in the spectra of the metals. The experimental atom to metal core level binding-ener gy shifts agree well with the predictions of the thermodynamical model by Johansson and Martensson.