Formation of Decacyclene Nanowire by Rapid Vapor Deposition

Abstract

Rapid vapor deposition of decacyclene, a polycyclic aromatic compound, on any substrate except for graphite has been found to produce cylindrical nanowires of decacyclene with uniform diameters of 40–70 nm and lengths of 1–10 µm that are further converted to conducting carbon nanofibers by ion beam irradiation. Detailed observation of the nanowires prepared under various conditions reveals that the nanowires grow on the surface of supercooled liquid droplets that are generated on the substrate by rapid condensation of decacyclene vapor. The nanowires grow toward the vacuum while keeping the growth plane beneath the surface. A controlling factor that keeps the diameter of each nanowire constant is the difference of the wettability between the growth plane and the lateral wall of the nanowire. Although the growth plane is always attached to the liquid due to the attractive interaction with the liquid, because of the repulsive interaction of the lateral wall with the liquid, the growing layer starts to emerge from the surface once the growing layer entirely covers the overlaying layer. The radial growth is very fast at the initial stage of nanowire formation, so that the diameter of the growing layer successively increases until the maximum diameter is attained. The nanowire is therefore cylindrical with a hemispherical tip.