Dynamical Studies of Ultrafast Charge Migration in Diatomic and Modular Molecules

May 18, 2016, 1:45 PM



Prof. francoise REMACLE (University of Liege Address)


The recent developments in the generation of optical attopulses suggest that it will soon become experimentally feasible to induce and subsequently directly probe ultrafast charge transfer between the end moieties of modular molecules. One ultrafast pulse creates a non-stationary state of the neutral or of the cation, that can be probed by a second pulse. Such experiments would allow characterizing a purely electronic time scale, before the coupling to the nuclei takes place. This is a pre Born-Oppenheimer regime where the electronic states are not stationary. 1 Our next goal is to investigate how the onset of nuclear motion and subsequently the fate of a chemical reaction can be controlled through the non equilibrium electronic density resulting from the interaction with a strong ultra short excitation pulse.

We will report on the simulation of realistic pump probe experiments that monitor the ultrafast electronic dynamics in LiH,[2,3] in the medium size bifunctional molecule PENNA (C10H15N)[4], C60[5] and other medium size molecules using a coupled equation scheme that includes the ionization continua and field effects. We will further illustrate how time and angular resolved photoelectron distributions provide an accurate probe of the electronic dynamics. We will then discuss the role of nuclear motion in the diatomic molecule LiH using full electron–nuclei quantum dynamics computation.[6] These recent computations show that the ultrafast beatings of the electronic coherences in space and in time are modulated by the different periods of the nuclear motion but survive for a large number of vibrational period[6]. Our results also show that dissociation to specific asymptotes can be controlled through the spatial localization of the non equilibrium density at the end of the excitation by a strong atto pulse.

Acknowledgments: This work has the support of FRFC 2.4545.12 (FR and BM), of DoE AMOS DE-SC0012628 (FR-RDL) and of the Einstein Foundation (RDL)

References 1 F. Remacle and R. D. Levine Proc. Natl. Acad. Sci. USA 2006, 103, 6793-6798. [2] B. Mignolet, R. D. Levine, F. Remacle Phys. Rev. A 2014, 88, 021403(R). [3] B. Mignolet, R. D. Levine and F. Remacle, J. Phys. Chem A 2014, 118 ,6721-6729. [4] B. Mignolet, R. D. Levine, F. Remacle J. Phys. B 2014, J. Phys. B: 47, 124011. [5] H. Li et al, Phys. Rev. Lett. 2015, 114, 123004. [6] A. Nikodem, R. D. Levine, F. Remacle, J. Phys. Chem. A, 2016, submitted.

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Prof. francoise REMACLE (University of Liege Address)

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