2019 Fiscal Year Research-status Report
Amplification of Chiral Light-Matter Interaction Using Bottom-Up 3D Chiral Nanoparticle
| Project/Area Number |
19K23594
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| Research Institution | Center for Novel Science Initatives, National Institutes of Natural Sciences |
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Principal Investigator |
AHN HyoYong 大学共同利用機関法人自然科学研究機構(新分野創成センター、アストロバイオロジーセンター、生命創成探究, 新分野創成センター, 特任助教 (70844348)
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| Project Period (FY) |
2019-08-30 – 2021-03-31
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| Keywords | chiral / plasmon / nearfield / nanoparticle / biomolecule |
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| Outline of Annual Research Achievements |
The major purpose of this research project is to develop a method for amplifying chiral light-matter interactions using bottom-up based 3D chiral nanoparticles as mediators. To achieve the goal, this research project is conducted through two research directions. [Direction 1] Investigation of a mechanism for the generation of a strong chiroptical signal of the plasmonic helicoid nanoparticle. [Direction 2] Nanoscale coupling between chiral nanoparticles and molecules. This year, we focused on Direction 1. Using gold helicoid nanoparticles which were chemically synthesized by the peptide-directed method, we observed a nearfield distribution of a single helicoid nanoparticle. A nearfield mapping of the degree of circular polarization proved that the chiral nearfield can be produced from the single helicoid nanoparticle. The generation and amplification of the chiroptical signal mediated by the helicoid nanoparticle were demonstrated by the two-photon-induced photoluminescence (TPI-PL) of gold. The single nanoparticle was exposed under the ultra-short pulse at NIR wavelength, and the polarized component of the TPI-PL signal at the visible wavelengths was observed. As a result, the single helicoid nanoparticle generated the circularly-polarized luminescence with a g-factor of 1.4 in maximum, which is a record-high degree of circular polarization for bottom-up synthesized nanoparticles. This result suggests the possibility of transferring the chirality to the nearby material and enhancing the chiroptical response at the surface of the nanoparticle.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
This research was originally planned for a 2-years project, and in the first year, we planned to investigate the mechanism for the generation of a strong chiroptical signal of helicoid nanoparticles. This year, we successfully observed the chiral nearfield effect of the single helicoid nanoparticle and the high-purity circular polarization of the photoluminescence of gold. In particular, it turned out that the g-factor of the photoluminescence was higher than that was initially expected. This property is advantageous for maximizing the chiroptical signal of molecules, which is a strong driving force for the research of the second year.
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| Strategy for Future Research Activity |
In the second year, we will study the unique chiroptical property of the molecule-nanoparticle coupled system. Using a gold helicoid nanoparticle as a host, various types of molecules, such as small organic molecules, molecular aggregates, small biomolecules, and proteins) will be localized on the surface of the nanoparticle to enhance the chiroptical response. By observing the change of the chiroptical signal, the analysis of the structural information of molecules will be attempted. In addition to the experiment, the numerical simulation for the detailed understanding of the generation of circularly-polarized luminescence will be conducted.
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| Causes of Carryover |
This year, we expensed 390000円 for the purchase of 1) chemical compounds for the synthesis of the nanoparticle and 2) optics for the generation of circular polarization because we focused on the investigation of the chiroptical property of chiral nanoparticles. The remaining amount (410000円) was saved for the purchase of various biomolecules in the second year, which is expected as the largest expense among the overall budget.
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Research Products
(4 results)
