Control of molecular photo-dynamics using plasmonic nano-vortex field

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H03882
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 30:Applied physics and engineering and related fields
• Research Institution: Hokkaido University
• Principal Investigator: Sasaki Keiji 北海道大学, 電子科学研究所, 教授 (00183822)
• Co-Investigator(Kenkyū-buntansha): 藤原 英樹 北海学園大学, 工学部, 教授 (10374670)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 光渦 / 局在プラズモン / 光の角運動量 / 禁制遷移 / 分子光ダイナミクス

Outline of Final Research Achievements

In this study, we developed a technique for creating novel plasmonic systems that not only focusing a light into the nanoscale region but also control the shape of light at the nano-scale. From our numerical analysis, we showed that gold trimer or tetramer structures can be used to focus optical vortex beam with complex angular momentum in the nano-region, and the CD spectra of the pseudo-chiral structure placed at the center of the gap area are enhanced. Based on the numerical results, we experimentally succeeded to observe the nano-scale orbital rotation of a trapped nanoparticle by using a nano-sized circularly-polarized optical field induced at the nano-gap. Additionally, we showed that the nano-sized circularly-polarized optical field has a strong effect on the crystallization process of sodium chlorate, resulting in a giant (greater than 50%) crystal enantiomeric excess (CEE).

Free Research Field

光計測操作

Academic Significance and Societal Importance of the Research Achievements

本研究の成果は、光を単にナノサイズに絞り込むだけでなく、分子・分子集合体の波動関数と光のナノ形状をマッチングさせることにより、禁制遷移の選択励起・許容遷移の完全抑制・均質媒質の第二高調波発生など、これまでの常識を打ち破る物質の光励起ダイナミクスや光反応プロセスが実現できると期待される。また、医薬品・農薬・香料の開発等、様々な分野において重要な課題となっているキラリティーの識別などの分野において光のナノ形状の制御により個々の分子・分子集合体を超高感度に計測する新規センシング技術に繋がるものと期待される。