UV-laser Treatment in the Nanodomain: Forming of Organic Nanofibers

Nanofibers grown in a sophisticated surface self assembly process from organic molecules are important key elements for future nanoscaled optoelectronic devices. They might serve both as passive elements such as waveguides and as active elements such as nanoscaled light sources or nanolasers. For both applications, structuring of the nanofibers by defined cutting is very important. However, as with all surface grown nanoaggregates, this is a difficult task when applying conventional mechanical cutting methods. In this article we show that excimer laser treatment at 193 nm provides a valuable alternative. We find that irradiation at a fluence of 100 mJ/cm removes the fibers completely without damaging the growth substrate mica. In addition, the fibers can be cut in any orientation relative to their long axes. Ablation and cutting work even better for nanofibers transferred onto other substrate surfaces such as glass. We investigate the quality of the ablation process in terms of nanofiber bleaching, substrate destruction and steepness of cutting by atomic force as well as fluorescence microscopy. It is shown that the imaging focus position has a critical influence on the steepness, with a so far limiting value of 400 nm.