IRRAS and LEED studies of films of the long chain n-alkane n-C44H90 on Cu(1 0 0) and Cu(1 1 0)

The film structures of the long chain n-alkane n-C44H90 on Cu(1 0 0) and Cu(1 1 0) were investigated by infrared reflection absorption spectroscopy (IRRAS) and low energy electron diffraction (LEED). The first layer on Cu(1 0 0) consists of the molecules oriented with the flat-on geometry where the carbon skeleton plane is parallel to the substrate. The molecular axes are arranged along [0 1 1] and [0-1 1] directions. On the other hand, the molecules in the first layer on Cu(1 1 0), which also adopt the flat-on geometry, are arranged with their molecular axes along only [1-1 0] direction, reflecting the in-plane anisotropy of the substrate surface. Noticeable difference in molecular orientation in the multilayers was not observed between the two substrates. The substrates affect only the first layers, and the surface symmetry restricts the molecular arrangement.