Interplay of vibrational wavepackets during an ultrafast electron transfer reaction

• Published in: Nature chemistry Vol. 13; no. 1; pp. 70 - 76
• Main Authors: Rather, Shahnawaz R., Fu, Bo, Kudisch, Bryan, Scholes, Gregory D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-01-2021; Nature Publishing Group
• Subjects: 639/638; 639/638/440; 639/638/440/947; 639/638/440/949; Acceleration; Analytical Chemistry; Biochemistry; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Coherence; Electron transfer; Electrons; Energy transduction; Energy transfer; Inorganic Chemistry; Organic Chemistry; Physical Chemistry; Reaction products; Spectroscopy; Vibrations; Wave packets
• ISSN: 1755-4330; 1755-4349; 1755-4349
• DOI: 10.1038/s41557-020-00607-9

Electron transfer reactions facilitate energy transduction and photoredox processes in biology and chemistry. Recent findings show that molecular vibrations can enable the dramatic acceleration of some electron transfer reactions, and control it by suppressing and enhancing reaction paths. Here, we report ultrafast spectroscopy experiments and quantum dynamics simulations that resolve how quantum vibrations participate in an electron transfer reaction. We observe ballistic electron transfer (~30 fs) along a reaction coordinate comprising high-frequency promoting vibrations. Along another vibrational coordinate, the system becomes impulsively out of equilibrium as a result of the electron transfer reaction. This leads to the generation (by the electron transfer reaction, not the laser pulse) of a new vibrational coherence along this second reaction coordinate in a mode associated with the reaction product. These results resolve a complex reaction trajectory composed of multiple vibrational coordinates that, like a sequence of ratchets, progressively diminish the recurrence of the reactant state.
Electronic–vibrational interplay can enable electron and energy transfer processes to be regulated. Now, coherence spectroscopy has been used to disentangle two vibrational pathways that control an electron transfer reaction. It has been shown that a fast, effectively ballistic, electron transfer along one vibrational path acts like a pulse to generate a coherent wavepacket along another vibrational pathway.