  The adsorption of thienylenevinylene oligomers on the Si(100) surface has
been investigated using scanning tunneling microscopy. The mode of substitution
of the thiophene ring exerts a strong influence on the adsorption
configurations and the images of the oligomer based on 3,4-dihexyl thiophene
are highly voltage dependent. We discuss the influence of the alkyl chains on
the adsorption process and on the appearance of the molecules in the STM
images.
