Capturing electron-driven chiral dynamics in UV-excited molecules

• 成果类型: Article
• 署名作者: Wanie, Vincent; Bloch, Etienne; Mansson, Erik P.; Colaizzi, Lorenzo; Ryabchuk, Sergey; Saraswathula, Krishna; Ordonez, Andres F.; Ayuso, David; Smirnova, Olga; Trabattoni, Andrea; Blanchet, Valerie; Ben Amor, Nadia; Heitz, Marie-Catherine; Mairesse, Yann; Pons, Bernard; Calegari, Francesca
• 署名单位: Helmholtz Association; Deutsches Elektronen-Synchrotron (DESY); Universite de Bordeaux; CEA; Centre National de la Recherche Scientifique (CNRS); CNRS - Institute of Physics (INP); University of Hamburg; University of Hamburg; Imperial College London; Leibniz Association; Max Born Institute for Nonlinear Optics & Short Term Spectroscopy; Technical University of Berlin; Leibniz University Hannover; Universite de Toulouse; Universite Toulouse III - Paul Sabatier; Centre National de la Recherche Scientifique (CNRS); Polytechnic University of Milan; University of London; Queen Mary University London
• 刊物名称: Nature
• ISSN/ISSBN: 0028-4285
• DOI: 10.1038/s41586-024-07415-y
• 发表日期: 2024-06-06
• 关键词: photoelectron circular-dichroism; time; photoionization; spectroscopy

摘要

Chiral molecules, used in applications such as enantioselective photocatalysis(1), circularly polarized light detection(2) and emission(3) and molecular switches(4,5), exist in two geometrical configurations that are non-superimposable mirror images of each other. These so-called (R) and (S) enantiomers exhibit different physical and chemical properties when interacting with other chiral entities. Attosecond technology might enable influence over such interactions, given that it can probe and even direct electron motion within molecules on the intrinsic electronic timescale(6) and thereby control reactivity(7-9). Electron currents in photoexcited chiral molecules have indeed been predicted to enable enantiosensitive molecular orientation(10), but electron-driven chiral dynamics in neutral molecules have not yet been demonstrated owing to the lack of ultrashort, non-ionizing and perturbative light pulses. Here we use time-resolved photoelectron circular dichroism (TR-PECD)(11-15) with an unprecedented temporal resolution of 2.9 fs to map the coherent electronic motion initiated by ultraviolet (UV) excitation of neutral chiral molecules. We find that electronic beatings between Rydberg states lead to periodic modulations of the chiroptical response on the few-femtosecond timescale, showing a sign inversion in less than 10 fs. Calculations validate this and also confirm that the combination of the photoinduced chiral current with a circularly polarized probe pulse realizes an enantioselective filter of molecular orientations following photoionization. We anticipate that our approach will enable further investigations of ultrafast electron dynamics in chiral systems and reveal a route towards enantiosensitive charge-directed reactivity.