ADSORBATE-INDUCED STRUCTURE TRANSITIONS AT THE RECONSTRUCTED PT(100) SURFACE

The perfection of the Pt(100)(1 x 1) surface depends on the adsorbate used for lifting the hexagonal reconstruction of this surface. It is generally claimed that H-2 adsorption at temperatures greater-than-or-equal-to 100 K leads to a poorly ordered, only ''(1 x 1)-like'' Pt(100) surface which together with desorption of the most strongly bound hydrogen state reconstructs again at 375 K. In turn, NO adsorption at room temperature followed by mild annealing is always reported to produce a more perfect Pt(100)(1 x 1) surface. In the present work we have reproduced these findings using LEED, TDS, work function measurements (DELTAphi) and photoemission of adsorbed xenon (PAX). But more importantly we also describe a procedure to prepare a perfect Pt(100)(1 x 1) surface using only hydrogen, which has the same properties as the NO-prepared surface.