Femtosecond near-field scanning optical microscopy study of molecular thin films

A near-field scanning optical microscope has been combined with a two-colour time-resolved pump-probe measurement system. It has a noise-equivalent transmittance change of 5.0 x 10-5 for a probe pulse with an intensity of 30 nW. The system has been used for evaluating molecular thin films that have a domain structure, particularly for observing a gate action of the single 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.