Abstract
Nanometer-scale processing of organic thin films by a scanning near-field optical microscope (SNOM) has been attempted for the purpose of high data storage so far. However, the mechanism is not clear yet. In this work, with the use of SNOM we succeed in microprocessing of perylene microcrystals caused by an excitonic effect. The dynamic change in the shape of the processed microcrystals is also observed after cutting off the near-field light. In the case of the double-layered microcrystals, the upper layer does not show any fluorescence, but the region becomes fluorescent after the near-field processing. This phenomenon is a clear demonstration of nano-scale optical writing and reading by means of SNOM.