| 研究実績の概要 |
1. Numerical simulation of plasmonics resonance in aluminum tip-film system: In order to extend the tenability of plasmonic resonances in the wavelengths smaller than 500 nm, we continued the 3D-FDTD simulations to understand the tunable behavior of the aluminum tip-film system.
2. Fabrication of tip-film system for silver: One of the practical issues was to obtain very flat silver surface, which was essential for good plasmon hybridization. While it was easy to obtain flat surface for gold, it was very difficult for silver. However, we were finally able to control the surface roughness of the silver film below 2 nm. Further, in order to keep a small gap between the tip and the film, we coated the tip with a 2-nm-thick layer of SiO2. Unfortunately, this part of the work consumed more time than what we had expected, and we could not grow aluminum tip-film system, which was our next target to extend the tenability range to lower wavelength.
3. Measurement of scattering spectrum: After fabrication of smooth layer of silver coated tip and film, we started the measurements of scattering spectrum for varying tip apex diameter and film thickness. We first fixed the diameter of the tip apex to 40 nm, and varied the silver film thickness from 4 to 24 nm, and measured the scattering spectra to observed the shift in scattering peak, which confirmed the tenability of plasmon resonance. This was then repeated for tips with apex diameter of 30 and 20 nm. We were successful in controlling and tuning the plasmon resonance for the tip-film system.
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