Pioneering femtosecond structural chemistry using X-ray Free Electron Laser

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K18944
• 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: Japan Synchrotron Radiation Research Institute
• Principal Investigator: Katayama Tetsuo 公益財団法人高輝度光科学研究センター, XFEL利用研究推進室, 主幹研究員 (90648073)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 核波束 / X線溶液散乱 / X線発光分光 / X線自由電子レーザー / 分子動画 / 溶媒和 / ダイナミクス / 光反応

Outline of Final Research Achievements

In this study, we have directly observed photo-induced pseudo-Jahn-Teller conformational changes of polypyridine copper(I) complex molecules in solution at atomic resolution by exploiting the uniqueness of the X-ray free electron laser, and experimentally mapped the trajectory of the excited molecules traversing on the potential energy surface. By utilizing time-resolved X-ray solution scattering, which directly observes the structural changes of the system projected in reciprocal lattice space, we tracked the structural changes of the complex (solute) and the surrounding solvent molecules (acetonitrile) in the first coordination sphere with sub-angstrom resolution. This elucidates the atomic-level mechanism of how the solute and surrounding solvent molecules interact with each other and structural changes proceed.

Free Research Field

光化学

Academic Significance and Societal Importance of the Research Achievements

溶液中では、反応物となる溶質だけでなく周囲に存在する溶媒が光反応に顕著な影響を及ぼすことは溶媒和効果として良く知られた現象である。しかし、原子レベルの動きとして溶質の構造変化が周囲にある溶媒分子をどのように動かすのか、また動いた溶媒分子が逆に溶質のダイナミクスにどのような影響を及ぼすのかについてはこれまでほとんど分かっていなかった。本研究の成果は時間分解X線溶液散乱がこの学術的な問いに答える有力な手法であることを示した。