Detection of molecular orientation via simultaneous bi-color movie of blinking surface-enhanced Raman scattering

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05671
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: The University of Tokyo (2018); Kwansei Gakuin University (2016-2017)
• Principal Investigator: Kitahama Yasutaka 東京大学, 大学院理学系研究科(理学部), 特任研究員 (00342775)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: １分子計測 / 光ピンセット / 超解像イメージング / 冪乗則 / 明滅現象 / 表面増強ラマン散乱 / 表面増強蛍光 / プラズモニクス

Outline of Final Research Achievements

Blinking surface-enhance Raman scattering and fluorescence (SERS and SEF), which are emitted from a molecule on and near the surface of a noble metal, respectively, were simultaneously observed in different wavelength regions. Then the bi-color movie was analyzed by a truncated power law. From the power-law exponents and the truncation times, we can estimate the behavior of the SERS- and SEF-active molecule.
Also from a fluctuation in the bi-color intensity ratios, the molecular behavior on and near the surface can be estimated. Moreover, it suggests single-molecule detection that SERS of an analyte was not observed while SEF of another analyte was emitted.
By super-resolution imaging, the precise positions of the SERS- and SEF-active molecule were detected. As the excitation laser intensity increased, the fluctuation of the positions was decreased. This indicates that the single molecule was optically trapped via plasmon-resonance.

Free Research Field

物理化学、分析化学、分子分光学

Academic Significance and Societal Importance of the Research Achievements

今回の二色同時動画の撮影と解析から、超高感度分析の極北である１分子計測ができているかを簡便に調べられることを示した。また、触媒反応で重要な金属表面・近傍での分子の動き方の違いも検討できることも示した。
さらに、今回の金属ナノ構造体表面での光圧捕捉では、単一分子を常温の溶液中でも操作できる。金属ナノ構造体の位置を精密に制御することは既存の走査型プローブ顕微鏡で可能である。その装置による光ピンセットを用いれば、非接触で分子を配置できる上に、表面増強ラマン散乱スペクトルから希望の分子を同定できるので、様々な分子を自由に組み合わせた分子素子の開発も可能となる。