DETERMINATION OF CA 2P IONIZATION THRESHOLDS BY HIGH-RESOLUTION PHOTOELECTRON-SPECTROSCOPY

The energies of the closely spaced Ca 2p thresholds have been determin ed by crossing an atomic beam of calcium with the monochromatized sync hrotron radiation from the high-resolution undulator beamline SX 700-B W3 at HASYLAB and analysing the kinetic energy of the outgoing photoel ectrons with a high-resolution SCIENTA SES 200 electron analyser. The experimental results are compared to the predictions of different theo retical approaches and the strong influence of electron correlation in the core ionized state is demonstrated.