2026-01-08 京都大学
フェノールやインドール分子が浮かんだ水の表面の超高速観測。真空中に導入した膜状の液体を使って水の表面で進む反応の速度を精密に測定できる。
＜関連情報＞
- https://www.kyoto-u.ac.jp/ja/research-news/2026-01-08-3
- https://www.kyoto-u.ac.jp/sites/default/files/2026-01/web_2601_Suzuki-55270334c729844ec1ff2d15a76b74b9.pdf
- https://pubs.acs.org/doi/10.1021/jacs.5c18369
超高速光電子分光法による水性界面における芳香族分子の電荷分離ダイナミクスの解明 Charge Separation Dynamics of Aromatic Molecules at Aqueous Interfaces Revealed by Ultrafast Photoelectron Spectroscopy
Yo-ichi Yamamoto,and Toshinori Suzuki
Journal of the American Chemical Society Published: December 31, 2025
DOI:https://doi.org/10.1021/jacs.5c18369
Abstract
Hydrophobic molecules can preferentially accumulate at the air–water interface, leading to interfacial concentrations far exceeding those in bulk solution and causing reactions to occur at higher rates. However, it remains unclear whether the reaction rate constants are intrinsically altered by the interfacial solvation environment. Here, we employ extreme ultraviolet time-resolved photoelectron spectroscopy (EUV-TRPES) to investigate the photoinduced charge-separation dynamics of the surface-active organic molecules indole, phenol, and phenolate. Ultraviolet photoexcitation of interfacial indole was found to produce both valence excited states and electron–cation contact pairs, both of which decayed faster than in the bulk solution. In contrast, interfacial phenol produced only valence excited states, with no detectable hydrated electrons or their precursors. Interfacial phenolate exhibited faster photodetachment than in the bulk solution. Both indole and phenol exhibit concentration-dependent dynamics due to interfacial molecular aggregation. These results contribute to a more comprehensive understanding of interfacial dynamics when considered alongside prior nonlinear optical spectroscopy studies. We further demonstrate EUV-TRPES with 18 fs time resolution, enabling direct observation of the 5 fs internal conversion of interfacial indole from the 1La to 1Lb state, followed by clear vibrational quantum beats. Thus, EUV-TRPES provides a powerful means for probing electronic and vibrational dynamics at interfaces.
