High harmonic interferometry of multi-electron dynamics in molecules

Abstract

High harmonic emission occurs when an electron, liberated from a molecule by an incident intense laser field, gains energy from the field and recombines with the parent molecular ion. The emission provides a snapshot of the structure and dynamics of the recombining system, encoded in the amplitudes, phases and polarization of the harmonic light. Here we show with CO(2) molecules that high harmonic interferometry can retrieve this structural and dynamic information: by measuring the phases and amplitudes of the harmonic emission, we reveal 'fingerprints' of multiple molecular orbitals participating in the process and decode the underlying attosecond multi-electron dynamics, including the dynamics of electron rearrangement upon ionization. These findings establish high harmonic interferometry as an effective approach to resolving multi-electron dynamics with sub-Angström spatial resolution arising from the de Broglie wavelength of the recombining electron, and attosecond temporal resolution arising from the timescale of the recombination event.

High-Harmonic Spectroscopy: From Femtosecond to Attosecond Molecular Dynamics

“…[15,16,19] Most remarkably, the strong laser field does not lead to a measurable distortion of the electronic wave functions within the accuracy of current experiments, even in polarizable systems like xenon [20] or in molecules with appreciable extension along the direction of the laser field like CO 2 . [4,5] The second step, propagation of the electron wavepacket, is largely dominated by the laser field and is well described by classical equations as evidenced by, e.g. the chirp of attosecond pulses.…”

“…The last few years have seen first successes in the observation of electronic dynamics on this time scale. [3][4][5][6][7] These techniques will enable a new experimental access to electronic structure and electron correlation, which is one of the most challenging problems in chemistry and physics.…”

“…This has been used to track the motion of protons on the attosecond time scale [17,18] and to study electron rearrangement following temporally confined ionization. [4][5][6] The most unusual aspect of these new methods is certainly the possibility to measure attosecond dynamics using multifemtosecond pulses. [2] This property originates in the extreme nonlinearity of the laser-matter interaction at high intensities.…”

Ultra-fast spin dynamics in the 2s2p2configuration of C+studied by time-dependentR-matrix theory

“…Finally, we demonstrated that the pump pulse length is a critical parameter for the observation of dynamics [17]. We note that features of high-harmonic spectra obtained from molecules have been assigned to correlated-electron dynamics [4,19]. Work is currently underway to develop theoretical understanding of these molecular effects through 2D models for diatomic molecules [20].…”

Electronic structure in real time: mapping valence electron rearrangements during chemical reactions

“…Following all electrons making the bonds while the bonds change would directly complement the insight from tracking electron dynamics on the attosecond time scale on the one hand (48,49) and nuclear dynamics on the femtosecond time scale on the other hand. It would give access to the coupled motion of electrons and nuclei during molecular dynamics (50).…”