Asymmetric photoreaction field using circular polarized light pf localized plasmon

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05053
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 32020:Functional solid state chemistry-related
• Research Institution: Hokkaido University
• Principal Investigator: Oshikiri Tomoya 北海道大学, 電子科学研究所, 特任准教授 (60704567)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: プラズモン / 近接場イメージング / 光電子顕微鏡 / キラリティ / 近接場スペクトル

Outline of Final Research Achievements

We have observed the chiral near-field distribution and the spectra on the series of achiral gold nano-rectangular structures (Au-NRs) under the circularly polarized light (CPL)irradiation by using multi-photon photoemission electron microscopy (MP-PEEM). We propose an interpretation that the chiral NF distribution is extrinsically generated on an achiral metallic nanostructure by the interference between two plasmonic modes by combining the state-of-the-art MP-PEEM techniques and classical oscillator model.
Additionally, by using time-resolved PEEM, the origin of chirality in plasmonic nanostructures could be directly revealed in the space and time domains with nanofemto scale resolution. The dynamic information on plasmonic modes, such as the resonance frequency and dephasing time for left and right CPL excitations were obtained by applying the interferometric time-resolved pump－probe technique, providing direct evidence for the spatiotemporal origin of chirality.

Free Research Field

光化学

Academic Significance and Societal Importance of the Research Achievements

本研究を遂行するに当たり、多光子光電子顕微鏡を用いてその空間分布およびスペクトル、緩和時間を高い空間・エネルギー・時間分解能で計測する手法を開発した。これは今後の近接場キラリティーの研究のモデルケースとなる方法論である。さらに、近接場キラリティの発現起源について、モード間干渉という新たな解釈を提案した。これは本研究に限定されるものでは無く、種々のプラズモンモードの近接場キラリティーの理解に貢献する。