Electron dynamics in biorelevant- and chiral molecules

Attosecond science is nowadays a well-established research field, which offers formidable tools for the realtime investigation of electronic processes. In this context, we have recently demonstrated that attosecond pulses can initiate electronic beatings in aromatic amino-acids [1]. Still, there is a long path towards attochemistry and the full control of the molecule via electronic coherences.

Sudden ionisation of a relatively large molecule can initiate a correlation-driven process dubbed charge migration, where the electron density distribution is expected to rapidly change. Capturing this few-femtosecond/attosecond charge redistribution represents the real-time observation of the electron correlation in the molecule. In this talk I will present a time-resolved study of the correlation-driven charge migration process occurring in the nucleic-acid base adenine after ionisation by a 15–35 eV attosecond pulse. We find that, the production of intact doubly charged adenine – via a shortly-delayed laser-induced second ionisation event – represents the signature of a charge inflation mechanism resulting from the many-body excitation. This conclusion is supported by first-principles time-dependent simulations [2].

I will also present a novel setup combining sub-2fs UV pulses with few-fs IR and attosecond XUV pulses. We recently have combined linearly polarized UV pulses with circularly polarized IR pulses to perform time-resolved Photo Electron Circular Dichroism (PECD) in Methyl-lactate and Ethyl-lactate. Our study shows an ultrafast dynamical inversion of the PECD which we assigned to the competition between the chiral response of different electronic states excited by the broadband UV pulse. A fast oscillation of the PECD also indicates the presence of a quantum beating between Rydberg states, modulating the chiral response of the molecule.

[1] F. Calegari et al, Science 346, 336 (2014)

[2] arXiv:2101.05753