Hybrid Scanning Near-Field Optical/Tunneling Microscopy with Indium-Tin-Oxide/Au Coated Optical Fiber Probe

The spatial resolution of a scanning near-field optical microscope (SNOM) is limited by its aperture size (50-200 nm). However, a hybrid system of a SNOM with a STM using a doubly metal-coated optical fiber probe could be used to overcome this limitation, resulting in a high-resolution feature. However, the throughput of such a probe was low because of the metal coating on the aperture. Authors developed a novel probe to overcome this disadvantage, where the metal coating on the aperture was replaced with an ITO coating. The performance of this probe was evaluated by examining isolated CdSe nanoparticles on an ITO substrate. Fluorescence from each nanoparticle was observed as a bright spot with the FWHM of about 20 nm, indicating high spatial resolution beyond the aperture size without sacrificing single-molecular-level high sensitivity. 22 refs.