Attosecond XUV probing of vibronic quantum superpositions in Br${}_2^{+}$

Abstract

Ultrafast laser excitation can create coherent superpositions of electronic states in molecules and trigger ultrafast flow of electron density on few- to sub-femtosecond time scales. While recent attosecond experiments have addressed real-time observation of these primary photochemical processes, the underlying roles of simultaneous nuclear motions and how they modify and disturb the valence electronic motion remain uncertain. Here, we investigate coherent electronic-vibrational dynamics induced among multiple vibronic levels of ionic bromine (Br${}_2^{+}$), including both spin-orbit and valence electronic superpositions, using attosecond transient absorption spectroscopy. Decay, revival, and apparent frequency shifts of electronic coherences are measured via characteristic quantum beats on the Br-$3d$ core-level absorption signals. Quantum-mechanical simulations attribute the observed electronic decoherence to broadened phase distributions of nuclear wave packets on anharmonic potentials. Molecular vibronic structure is further revealed to be imprinted as discrete progressions in electronic beat frequencies. These results provide a future basis to interpret complex charge-migration dynamics in polyatomic systems.

arXiv comment8 pages, 4 figures

References in corpus (6)

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• Semiclassical Theory of Coherence and Decoherence
• High-harmonic probing of electronic coherence in dynamically aligned molecules
• Coherent electronic-vibrational dynamics in deuterium bromide probed via attosecond transient absorption spectroscopy
• Coherence revival during the attosecond electronic and nuclear quantum photodynamics of the ozone molecule

Cited by in corpus (8)

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• Theoretical analysis of the role of complex transition dipole phase in XUV transient-absorption probing of charge migration
• Coherence from multiorbital tunneling ionization of molecules
• Probing Vibronic Coherence in Charge Migration of Molecules Using Strong Field Sequential Double Ionization
• Core-excited states of SF${}_6$ probed with soft X-ray femtosecond transient absorption of vibrational wavepackets
• Attosecond Probing of Coherent Vibrational Dynamics in CBr${}_4$
• Optical Interference Effect in Strong-field Electronic Coherence Spectroscopy
• Nonadiabatic theory for subcycle ionic dynamics in multielectron tunneling ionization