| 研究課題/領域番号 |
26600014
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| 研究機関 | 大阪大学 |
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研究代表者 |
VERMA Prabhat 大阪大学, 工学(系)研究科(研究院), 教授 (60362662)
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| 研究期間 (年度) |
2014-04-01 – 2017-03-31
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| キーワード | ナノプローブ |
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| 研究実績の概要 |
In this year of the project, we have achieved the following:
1. Numerical simulation:This research requires a thin silver coating on a SiO2 nano-tip, and fabrication of the grating on the tip, which acts like a plasmon coupler. In continuation with the simulation work done in the previous year, we continued further 3D-FDTD simulations to optimize the film thickness and the parameters of the plasmon coupler and obtained satisfactory results.
2. Fabrication of plasmonic tip:The plasmonic nano-tips used in this study are made from commercially available AFM Si cantilever tips. In the first step, we oxidized the Si tips at high temperature, so that the material of the tip changed from Si to SiO2. The oxidized tips were coated on the one side with thin layer of silver via high vacuum evaporation. The challenge lied in obtaining very smooth surface of silver with only one side of coating, which we completed successfully. Finally, be means of focused ion beam (FIB) technique, we created a grating, which was optimized through the simulation method, at a distance of 6 m from the tip apex.
3. Measurement of nano-focusing and nano-imaging:After fabrication of the plasmonic tip for plasmon nanofocusing, we utilized these tips to confirm their features. By shining laser at the plasmon coupler, we observed the creation of nano-light at the apex of the tip. This was then confirmed by measuring scattering spectrum. We applied these tips to perform high-resolution near-field scanning optical microscopy (NSOM) on CNT samples and confirmed high-contrast, high-resolution nano-imaging.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
As of now, we have successfully completed most of the work we proposed in this project, except the tip-enhanced Raman scattering (TERS) measurements using our fabricated tips. We successfully completed the simulation and fabricated the plasmonic tips in accordance to the results obtained from the simulation. Through confocal optical measurements, we confirmed the creation of nano-light via plasmon nano-focusing at the apex of the tip. This was further measured using scattering spectrum to investigate the plasmon resonance wavelength. Finally, we utilized the nano-light source to measure NSOM image of CNT.
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| 今後の研究の推進方策 |
We have already achieved most of the expected goals of creating nano-light source at the apex of a nano-tip and utilize it to measure near-field optical nano-images of various samples. We have successfully measured the NSOM images of CNT, however, could not finish the tip-enhanced Raman scattering (TERS) imaging utilizing the nano-light created at the tip apex. Since in this research the laser is focused at the plasmon coupler far from the sample, one of the biggest advantages is that we do not need to shine the sample directly with the laser. Rather, only the nano-light created at the tip apex illuminates the sample. This is expected to provide background-free TERS, resulting in nanoimages with extremely high contrast. Therefore, this is of great interest to utilize our fabricated tips to measure TERS from various samples. In the last year, we want to preform TERS measurements using our fabricated tips. In addition, we also want to extend this research to white light, where we expect to create a white-nano-light source at the tip apex, and utilize it for high quality color nanoimaging in a wide spectral range.
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| 次年度使用額が生じた理由 |
Our research was a bit delayed as we unexpectedly spent longer time on the experimentally obtaining the required surface quality of the film. In order to avoid losses during plasmon nano-focusing, it is necessary to have very smooth silver coating with an average surface roughness of about 1 nm. It was extremely difficult to obtain such smooth surface for silver and we spent long time in exploring all the possibilities in optimizing the deposition parameters. Finally, we were able to obtain low surface roughness, but the next steps were delayed because of this. Even though we could still achieve almost all the goals we had expected, we could not finish TERS measurements with our fabricated tips that create nano-light source at the apex.
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| 次年度使用額の使用計画 |
Since such tips are expected to produce high-contrast and high-quality nanoimaging in TERS, we would like to carry forward this project for one more year and complete the remaining work. If time permits, we would also like to utilize this technique to create white-nano-light source. In order to finish all this work, we need one more year, and would like to extend this project for one more year and carry forward the remaining money of this project to next year.The remaining grant of this project for the last year will be utilized for three purposes-1.For purchasing consumable items required for the research planned for this year.2.For publications related to this project.3.For attending domestic and international conferences to present the research achievements under this project
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