Arrangement of metal phthalocyanines on Ge (0 0 1) 2 × 1 surfaces

For monolayer films of metal phthalocyanines deposited on the two-domain Ge (0 0 1) 2 × 1 surface, NEXAFS measurements indicate that the molecules are tilted at an angle of 24–26° to the substrate. This result is further investigated here using NEXAFS and STM. First, the NEXAFS experiments previously carried out on the two-domain surface were repeated on a single domain Ge (0 0 1) 2 × 1 surface: it was found that NEXAFS perpendicular and parallel to the dimer rows were almost identical. Second, STM measurements indicate that most molecules adopt a unique bonding site, relative to the dimer rows and with the plane of the molecule parallel to the surface; however, some other bonding locations are also observed. Together these experiments suggest that a uniform molecular tilt is not an appropriate description; other possible explanations are briefly considered.