BONDING GEOMETRY AND ELECTRONIC-STRUCTURE OF THE CHALCOGENS ON NI(111)

The behavior of oxygen, sulfur, selenium, and tellurium on Ni(111) has been investigated using angular-resolved photoemission, LEED, programmed thermal desorption, and work function measurements. The synthesis of these measurements suggest bonding in a site of C//3//v symmetry and the existance of three nondegenerate orbitals participating in the nickel-chalcogen bond. Changes which occur in orbital energy levels as the adsorbate is varied from oxygen to tellurium are explained in terms of a tight-binding calculation of chalcogen bonding to a triangular cluster of nickel atoms in a pyramidal configuration.