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 studied in-situ scanning tunneling microscopy (STM). After low coverage depositions, molecular sized complexes of linear dimensions between 50 and 200 Å were observed. Some internal structure of the polymer conglomerates was resolved, revealing a "C" shaped cluster with a central depression. In some instances, a boundary between these clusters and long cigar shaped polymeric molecules was found. These "cigars" are approximately 400 Å long, but were not highly resolved. The general appearance of the deposited complexes suggests the chemically active evaporated oligomers are reacting on the substrate, building up these conglomerates in the process. Higher resolution scans of individual clusters show single polymer helices, and cross-linking between adjacent polymer chains.