Spontaneous rearrangement of para-sexiphenyl crystallites into nano-fibers

In the growth of para-sexiphenyl films on mica(001), an interesting phenomenon was observed where small individual crystallites spontaneously arrange into parallel running high-aspect ratio chains with a length in the micrometer range. A statistical analysis of the chain dimensions reveals a very narrow length distribution and the existence of a threshold length. The observation of denuded zones around the chains and the interior chain structure suggest a rearrangement of the crystallites as entities. It is proposed that this spontaneous rearrangement is driven by the formation of a one-dimensional defect array which evolves within the monomolecular para-sexiphenyl wetting layer when a critical crystallite density is reached.