BOND STRETCHING AND DISTORTION IN LARGE ORGANIC MOLECULES ON Ag(111) DETERMINED BY SURFACE X-RAY DIFFRACTION

Abstract

The geometric structure of large organic molecules (end-capped quaterthiophene and 2-thiouracil) adsorbed on Ag(111) was analyzed in detail by surface X-ray diffraction. In both cases our data give direct evidence for significant stretching of the C–S and the C–C bonds by up to 0.16 Å and — in the case of EC4T — for a distortion of the thiophene rings. This is in contrast to the common belief that such molecules remain undistorted upon adsorption on a weakly interacting substrate. Our results provide the basis for a deeper understanding of large organic adsorbates and have important implications for a deeper insight into organic/inorganic interfaces in general.