ELECTRONIC-STRUCTURE EFFECT ON CORE-LEVEL EXCITATION AND CHARGE-TRANSFER IN IONS SCATTERING FROM ALKALI-METAL-COVERED SURFACES

Strong electron emission from the decay of the Na(2p(5)3s(2)) state h as been found in low-energy (0.3-2-keV) Li+ collisions with Na-covered metal surfaces. The results show that at the initial oxygen adsorptio n, the formation of the core-excited Na state is rapidly reduced as t he work function decreases, which is attributed to the decreased proba bility of promoting core electrons into empty surface states between t he Fermi level and the vacuum level. The Li- spectra versus oxygen exp osure demonstrate that the initial oxygen adsorption increases the ele ctron-capture probability of the ions in the exit trajectory.