Photofluidic near-field mapping of superspherical gold nanoparticle (Conference Presentation)

Near field scanning optical microscopy (NSOM) has been used in many fields to see the optical properties of various materials with highly improved resolution over the diffraction limit. On the other hand, an alternative way to measure the optical properties of nanostructures were proposed using photosensitive polymer. By irradiation irradiating light on certain nanostructures on photosensitive polymer, electric field can be recorded depending on the irradiation time, intensity or nanostructure. [1] Though this method has some limits compared to the conventional NSOM, it gives high spatial resolution with relatively simple setup. Until now, most of the researches were done by simply coating photosensitive polymer on nanostructure or nanoparticles. Here, we measured near field intensity of superspherical gold nanoparticles (AuNPs) by varying the embedding depth of AuNPs in photosensitive polymer. Changed electric field from as transferred one (non-embedded) to fully embedded one was measured by Atomic Force Microscopy (AFM). By simply changing the irradiation angle on AuNPs, we mapped angle-dependent localized near field. Also, we placed thin gold film underneath the photosensitive polymer to measure image dipole of AuNPs. Furthermore, sub-nanometer gap from monolayer graphene can be differentiated by placing graphene sheet between gold film and polymer. Along with single AuNP, near field mapping of AuNP dimers were also measured by varying the interparticle distance. Finally, near field mapping of simple artificial structures manipulated with AuNPs for possible plasmonic applications were measured.