Development of spectroscopy that detects transient species with high sensitivity and high time-resolution

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K20365
• Project/Area Number (Other): 18H05351 (2018-2019)
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Multi-year Fund (2020); Single-year Grants (2018-2019)
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Gakushuin University
• Principal Investigator: Iwata Koichi 学習院大学, 理学部, 教授 (90232678)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: ラマン分光法 / 時間分解測定 / 化学反応

Outline of Final Research Achievements

The aim of this research was to develop a time-resolved spectroscopy for the detection of transient chemical species with a high sensitivity and a high time-resolution. For this purpose, a stable picosecond time-resolved Raman spectrometer was first developed. Stable outputs from a femtosecond laser system were used as a light source for this spectrometer. Vibrational relaxation processes of terthiophene in the first excited singlet state was observed on gold or silver nanoparticles with this spectrometer. The results indicated the presence of mode-specific fast vibrational energy transfer between the electronically excited terthiophene and the metal nanoparticles. Energy transfer mechanism based on the intra- and inter-molecular vibrational coupling was proposed from these findings.

Free Research Field

分光物理化学

Academic Significance and Societal Importance of the Research Achievements

新たな方式を採用した高安定ピコ秒時間分解ラマン分光計の出力安定性は二乗平均平方根0.8％であり，周波数・時間積はフーリエ変換限界の1.2から1.3倍であった．このピコ秒時間分解ラマン分光計の開発を報告した論文は国際学術誌で高い評価を受けて，カバー論文に選ばれた．この分光計を利用することで観測できた電子励起ターチオフェン分子の金および銀ナノ粒子近傍における振動緩和過程は，分子内および分子間の振動相互作用に誘起されたエネルギー伝達機構の存在や金属ナノ粒子によるモード選択的な振動位相緩和の加速やねじれ構造の緩和を示唆する重要な現象であった．