HYDROGEN-INDUCED RECONSTRUCTION OF A W(110) SURFACE STUDIED BY ANGLE-RESOLVED PHOTOEMISSION SPECTROSCOPY

We have observed changes in the electronic structure of a W(110) surface caused by the hydrogen-induced reconstruction using angle-resolved photoemission spectroscopy. For the unreconstructed H/W(110) surface, a number of hydrogen-induced states are observed, and some of them are found to be in the projected bulk band gap. As W(110) undergoes the surface reconstruction induced by further hydrogen adsorption, one of those states is rapidly quenched, while others simply shift downward in energy by a fraction of an electron volt. To understand the surface reconstruction mechanism for this system, the surface electronic states before and after the surface reconstruction are calculated using the ''simple'' tight-binding method. The driving mechanism for the hydrogen-induced surface reconstruction is briefly discussed.