Reflection high-energy electron diffraction study of surface morphology of vicinal Au(1 1 0) throughout the (2 × 1) to (1 × 1) phase transition

The vicinal Au(1 1 0) surface morphology throughout the (2 × 1) to (1 × 1) phase transition is studied by quantitative reflection high-energy electron diffraction. As the surface is heated from 300 K, the average terrace width remains unchanged up to 635 ± 10 K. Above that temperature, the average terrace width increases and at 683 K has a value (34 ± 10)% more than at 300 K. At higher temperatures, the average terrace width decreases. The average string length at step terraces on Au(1 1 0) remains basically unchanged up to ∼650 K and decreases sharply at higher temperatures indicative of a step-induced roughening transition. Thermal-induced adatom/vacancy generation on terraces is shown to increase significantly above ∼680 K. At room temperature, the spacing between the topmost two layers of the Au(1 1 0) surface is contracted by 0.31 ± 0.03 Å or ∼22% of the bulk-terminated structure.