Surface reconstruction of Pt(001) quantitatively revisited

Abstract

The complex hexagonal reconstructions of the (001) surfaces of platinum and gold have been under debate for decades. Here, the structural details of the Pt(001) reconstruction have been quantitatively reinvestigated by combining the high resolving power of scanning tunneling microscopy (STM) and spot profile analysis low energy electron diffraction (SPA-LEED). In addition, LEED simulations based on a Moir\'e approach have been applied. Annealing temperatures around 850 \ifmmode^\circ\else\textdegree\fi{}C yield a superstructure that approaches a commensurable $c(26.6\phantom{\rule{0.16em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.16em}{0ex}}118)$ substrate registry. It evolves from a Moir\'e-like buckling of a compressed hexagonal top layer (hex) where atomic rows of the hex run parallel to atomic rows of the square substrate. Annealing at 920 \ifmmode^\circ\else\textdegree\fi{}C stimulates a continuous rotation of the hex where all angles between \ifmmode\pm\else\textpm\fi{}0.7\ifmmode^\circ\else\textdegree\fi{} are simultaneously realized. At temperatures around 1080 \ifmmode^\circ\else\textdegree\fi{}C, the nonrotated hex coexists with a hex that is rotated by about 0.75\ifmmode^\circ\else\textdegree\fi{}. Annealing at temperatures around 1120 \ifmmode^\circ\else\textdegree\fi{}C yield a locking of the hex in fixed rotation angles of 0.77\ifmmode^\circ\else\textdegree\fi{}, 0.88\ifmmode^\circ\else\textdegree\fi{}, and 0.94\ifmmode^\circ\else\textdegree\fi{}. At temperatures around 1170 \ifmmode^\circ\else\textdegree\fi{}C, the Pt(001)-hex-R 0.94\ifmmode^\circ\else\textdegree\fi{} prevails as the energetically most favored form of the rotated hex.