Femtosecond near-field scanning optical microscopy study of molecular thinfilms

A near-field scanning optical microscope has been combined with a two-colou r time-resolved pump-probe measurement system. It has a noise-equivalent tr ansmittance change of 5.0 x 10(-5) for a probe pulse with an intensity of 3 0 nW. The system has been used for evaluating molecular thin films that hav e a domain structure, particularly for observing a gate action of the singl e domains. The results include key features to understand an origin of the domains and suggest that the film composition is uniform over a distance of several micrometres.