Near-Field Optical Characterization of Sub-Micrometer Paricle Arrays of Organic Dye
Akihiro Tomioka, Tasuyuki ido, Yasuaki Itakura and Tooru Motokubota
We performed near-field optical studies of the self-organized particle arrays prepared by a wetting/dewetting procedure. Suppressing the background fluorescence we identified the near-field fluorescence from separated particles. However some of the particles, especially most of small particles with diameter less than 2 µm, did not show fluorescence under near-field observation. Far-field fluorescence, when excited by polarized evanescent field, revealed that there were many regions in the specimen where molecule’s transition moment oriented parallel to the substrate surface. These two observations suggest that the near-field at the tip of the probe polarized parallel to the probe axis. Another observation that molecules seemed to orient to similar direction among particles within these regions suggests that dewetting process contributes to align molecular direction among neighboring particles, which further justifies that the present specimen was formed by a self-organizing mechanism.