Development and demonstration of evaluation model for strong coupling plasmons and molecules in plasmonic hotspots

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04988
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 30020:Optical engineering and photon science-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Itoh Tamitake 国立研究開発法人産業技術総合研究所, 生命工学領域, 上級主任研究員 (00351742)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 強結合 / プラズモン / 表面増強ラマン / 表面増強蛍光

Outline of Final Research Achievements

The place of several nm ^ 3 at the gap between two nanoparticles such as gold and silver is called a hot spot (HS). In HS, the density of states of light increases due to the resonance between plasmons and electromagnetic fields, making it possible to observe extreme phenomena such as strong coupling between single molecule polarization and plasmon polarization and ultrafast fluorescence. However, theoretical and experimental methods that can quantitatively evaluate these phenomena are still under development. In this study, we developped a cavity quantum electrodynamics (QED) model that includes "multi-level properties of molecules" and "higher-order plasmon modes". The model quantitatively reproduced the experimental results of enhanced Raman and fluorescence spectra of molecules in the HS under strong coupling.

Free Research Field

プラズモニクス

Academic Significance and Societal Importance of the Research Achievements

数ナノメートル以下の領域に光を閉じ込めて分子と相互作用させると、自由空間における相互作用とは大きく異なる振る舞いを示す。例えば、真空電磁場との強い相互作用で分子の励起状態の性質を大きく変化させて新しい機能を持たせることもできる。本研究成果の学術的意義は銀ナノ粒子二量体間隙がその様な場として利用できる可能性があることを示したことである。また、社会的意義は、従来は余り関心を持たれなかった電磁場のゼロ点振動である真空揺らぎの振幅を増強することで物質の性質を操作できる可能性を示したことである。真空揺らぎの応用光学として新規材料開発に結び付くことが期待できる。