Structure and roughening of the Pt(110) surface

X-Ray diffraction using synchrotron radiation from the National Synchrotron Light Source at Brookhaven has been used to study the clean Pt(110) surface prepared in ultrahigh vacuum. Three-dimensional crystallographic data show the structure to be ‘missing row’ with alternate [01] rows of atoms vacant in the top layer. Significant lateral relaxations are seen down to the fourth layer. Above 1080 K the surface undergoes a phase transition somewhat like that of Au(110). However, a distinct shifting of the half-order peak reveals the transition to involve the appearance of surface steps, and so it must be classified as a roughening transition instead of a simple 2D Ising model.