α-Sexithiophene Films Grown On Cu(110)-(2x1)O: From Monolayer To Multilayers

Abstract

The growth of a-sexithiophene (6T) on copper (110) and oxygen reconstructed Cu(110) is studied by multiple techniques such as STM (scanning tunnelling microscopy), XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy) and NEXAFS (near edge X-ray absorption fine structure). Selected data will be presented here and we will show that the long axes of the molecules on Cu(110) and Cu(110)-(2x1)O (CuO) are aligned along the valleys of the surface corrugations, i.e. along [1–10] and [001], respectively. With GIXD (grazing incidence X-ray diffraction) measurements the monolayer structure of 6T on Cu-O could be determined. Thicker films were studied by the X-ray diffraction pole figure technique. On all surfaces the (010) net planes of the bulk crystal structure are parallel to the surface i.e. the films grow exclusively (on Cu-O) or pre- dominantly (on Cu) in the (010) orientation. In the thick film the long molecular axes of the 6T molecules are found to be parallel to those of the monolayer. To study the transition from the monolayer to the multilayer structures NEXAFS measurements were carried out.