Single-nanomaterial absorption spectroscopy based on photomechanical response

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K19057
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Osaka University
• Principal Investigator: Ito Syoji 大阪大学, 基礎工学研究科, 准教授 (10372632)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 単一ナノ粒子分光 / 単一分子分光 / 光圧 / 光マニピュレーション

Outline of Final Research Achievements

As a sample for detecting photon pressure due to the photo-absorption by a small number of molecules, we used photochromic dyes the absorption coefficient of which can be remotely control by UV irradiation in a single particle.
A single particle with the photochromic dye was optically trapped in water with visible laser and irradiated with UV light to induce the coloration leading to the generate of absorption force. The force pushed the particle toward the light propagation direction and the slight shift (tens - hundreds of nm) was detected. By calculating the photon pressure acting on the particle, we concluded that photo-absorption by hundreds - thousands of molecules can be detected by using this technique. Based on this achievement, we proposed a new hybrid-optical manipulation combining photon force and photochemical reactions.
In conclusion, we have successfully developed an important tool for the realization of absorption spectroscopy based on the measurement of photon pressure.

Free Research Field

ナノ光化学

Academic Significance and Societal Importance of the Research Achievements

一般に，少数分子の検出には蛍光検出が用いられるが，必ずしも全ての化学種を測定できるわけではない。一方，吸収分光はより一般的な分光手法であり，原理的に全ての分子が検出可能である。しかし一般の吸収分光では試料入射前後の光強度差を検出するため，少数分子（単一分子から1000個程度）を対象とした吸収分光は一般には困難である。本研究では，分子が光を吸収するさい発生する微弱な力を検出し少数分子の吸収分光を可能にする新たな分光法を開発するものであり，分子やナノ材料の挙動を無染色で検出可能とする。これは材料科学や分子細胞生物学，分析化学などの幅広い分野に全く新しいナノ測定手法を提供できる。