Attempt to pile up extrathin sashlike macromolecules (atomic sashes)

Long-chain molecules vapor deposited onto cooled graphite lie flat and form a monolayer. When such a monolayer of 17,19-hexatriacontadiyne (HTDY) is irradiated with UV light, a surface topochemical reaction takes place to convert the molecules into a single sheet of a sashlike macromolecule (atomic sash) comprising the rows of alkyl chains bridged by a polydiacetylene chain. We attempted to pile up the atomic sashes by repeating the vapor deposition and UV irradiation, characterizing the products at all stages by Penning ionization electron spectroscopy. It is found that the aggregation of alkyl chains in the outermost layer (atomic sash or HTDY) is essentially unchanged up to approximately three layers independent of whether the underlying layer is graphite or the atomic sashes. (C) 1998 Elsevier Science B.V.