3. Self-Assembled Array of Atoms and Molecules on Metals

Molecules adsorbed on a metal surface are stabilized on the surface by adsorption or by reacting with surface atoms. By either adsorption or by reacting with surface atoms, they provide new chemical materials. A typical example is a two-dimensional crystal layer of n–C₁₇H₃₆ and n–C₃₆H₇₄ molecules formed on a (22 × √3)-Au(111) surface. They make a two-dimensional eutectic crystal layer on a (22 × √3)-Au(111) surface, which is an interesting two-dimensional new material. As discussed in Chap. 9, the phenomenon is similar to the formation of an ordered new alloy layer on a Pt–Rh(100) surface at 490  K in O₂, although Pt–Rh is a random mixing alloy. The reaction of adsorbed atom or molecule with surface atoms provides additional new two-dimensional materials named as “quasi-compound” in Chap. 4.