Figure 6.

Surface stress change during exposure of Cu(001) to oxygen at 300 K (blue curve) and 500 K (red curve). The resulting LEED patterns (E = 115 eV) after oxygen exposure show the diffraction pattern of the missing row $(\sqrt{2}\times 2\sqrt{2})\text{R}45°$ structure (upper image) and the c(2 × 2) structure (lower image). Exposure to O₂ was performed at a partial pressure of order 10⁻⁶ mbar, and it is given in Langmuir (1 L = 10⁻⁶ torr s).