We observed the physical vapor transport growth of tetracene (C 18 H 12 ) using a transparent furnace. We found that free-standing small crystals are formed in the gas flow and sometimes stick on the solid surface and become the seeds for larger crystals. A theoretically predicted convection was observed by tracking the trajectory of flowing crystal particles. #

We report a method to produce vapor species from ZnO powder for the fabrication of ZnO nanorods. Mixing ethanol vapor with the inert carrier gas substantially lowered the gasification temperature of ZnO.c-axis aligned ZnO nanorods were obtained by dispersing gold nanoparticles on Si substrates. The growth was identified as a vapor-solid (VS) mechanism. Choice of the substrate materials and their surface morphology were both critically important to control the shapes and orientation of grown ZnO.2