Laser-controlled growth of needle-shaped organic nanoaggregates

Arrays of mutually parallel oriented, single-crystalline, needle-like structures of light-emitting p-hexaphenyl molecules are generated in the focus of an argon ion laser. The cross sectional dimensions of the needles are of the order of 100 to 200 nm with lengths up to several hundred micrometers. While the orientation of the individual molecules in the needles is defined by the direction of surface dipoles, the localization on the surface, the length distribution as well as mutual distances can be adjusted via size and position of the laser focus spot.