IN-SITU SCANNING-TUNNELING-MICROSCOPY ON VAPOR-DEPOSITED POLYANILINE THIN-FILMS

Small amounts of polyaniline powder have been evaporated under vacuum onto gold coated mica substrates. The initial deposition has been stud ied in-situ using scanning tunneling microscopy (STM). After low cover age depositions, molecular sized complexes of linear dimensions betwee n 50 and 200 Angstrom were observed. Some internal structure of the po lymer conglomerates was resolved, revealing a ''C'' shaped cluster wit h a central depression. In some instances, a boundary between these cl usters and long cigar shaped polymeric molecules was found. These ''ci gars'' are approximately 400 Angstrom long, but were not highly resolv ed. The general appearance of the deposited complexes suggests the che mically active evaporated oligomers are reacting on the substrate, bui lding up these conglomerates in the process. Higher resolution scans o f individual clusters show single polymer helices, and cross-linking b etween adjacent polymer chains.