ADSORBATE-ADSORBATE INTERACTIONS IN NA COVERED MG SURFACES

We present a study on alkali cluster formation induced by ion bombardm ent, the information being obtained by Collisionally Excited Autoioniz ation Electron Spectroscopy (CEAES). We show that a uniform alkali fil m on a metal surface can be easily converted in large patches by low e nergy ion bombardment. The observed phenomenon is coverage dependent, in fact, for alkali density below a critical value the adlayer is unif ormly removed. Beyond this critical value a rearrangement mechanism le ads to the formation of extended adatom aggregates revealed by the spl itting in two components of both Ne and Na autoionization lines. A Mg atomic structure is also revealed in the spectrum, and, according to o ur interpretation model, no splitting is observed for this peak due to slow excited atoms.