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arXiv · 1712.02993

Electron--Proton Decoupling in Excited-State Hydrogen Atom Transfer in the Gas Phase

Mitsuhiko Miyazaki·Ryuhei Ohara·Kota Daigoku·Kenro Hashimoto·Jonathan R. Woodward·Claude Dedonder·Christophe Jouvet·Masaaki Fujii
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Abstract

Hydrogen-release by photoexcitation, excited-state- hydrogen-transfer (ESHT), is one of the important photo- chemical processes that occur in aromatic acids and is responsible for photoprotection of biomolecules. The mecha- nism is described by conversion of the initial state to a charge- separated state along the O(N)-H bond elongation, leading to dissociation. Thus ESHT is not a simple H-atom transfer in which a proton and a 1s electron move together. Here we show that the electron-transfer and the proton-motion are decoupled in gas-phase ESHT. We monitor electron and proton transfer independently by picosecond time-resolved near-infrared and infrared spectroscopy for isolated phenol--(ammonia)5, a benchmark molecular cluster. Electron transfer from phenol to ammonia occurred in less than 3 picoseconds, while the overall H-atom transfer took 15 picoseconds. The observed electron-proton decoupling will allow for a deeper understanding and control of of photochemistry in biomolecules

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Mitsuhiko Miyazaki, Ryuhei Ohara, Kota Daigoku, Kenro Hashimoto, Jonathan R. Woodward, Claude Dedonder, Christophe Jouvet, Masaaki Fujii. 2017-12-08. Electron--Proton Decoupling in Excited-State Hydrogen Atom Transfer in the Gas Phase. https://doi.org/10.1002/anie.201506467

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