Pulse‐Train Photoelectron Spectroscopy of Electronic and Nuclear Dynamics in Molecules

Abstract

We theoretically study the application of a femtosecond pulse train to simultaneously probe the electronic excitation dynamics and nuclear vibrational motion in the excited-state LiH molecule by means of time-resolved photoelectron spectroscopy. The step-like population transfers caused by continual interaction with a sequence of pulses and refractory periods are shown to give rise to time evolution of the photoelectron kinetic energy distribution as the history of molecular electronic and vibrational states. Such a signal should lead to a novel and direct way to investigate electronic and nuclear simultaneous dynamics involving multiple excited states.

Quantum Nuclear Dynamics Pumped and Probed by Ultrafast Polarization Controlled Steering of a Coherent Electronic State in LiH

“…The potential energy curves, V i ( R ) in eq , of the lowest five Σ and two Π adiabatic states below the IP (7.8 eV) are plotted in Figure . Our computational results follow already reported trends. ,, The Π states are fully repulsive. Only the lowest excited state Σ 1 of the Σ manifold is bound, with a shallow well.…”

“…Our computational results follow already reported trends. 8,50,62 The Π states are fully repulsive. Only the lowest excited state Σ 1 of the Σ manifold is bound, with a shallow well.…”

“…The early computations , on LiH sought a very accurate representation of the electronic state but were carried out with the nuclei frozen at the ground-state equilibrium position. More recent studies include nuclear dynamics. − In refs and , the multiconfiguration electron-nuclei dynamics (MCEND) methodology was used to investigate the electron nuclei dynamics following excitation by a 4 fs UV pulse for the first 15 fs. The authors concluded that limited nuclei motion takes place and that the frozen nuclei approximation holds during that time.…”

“…The authors concluded that limited nuclei motion takes place and that the frozen nuclei approximation holds during that time. In ref , quantum electron–nuclei dynamics is pumped by a several femtosecond UV pulse and probed by computing time-resolved photoelectron spectra resulting from ionization by a femtosecond pulse train. Here we discuss the quantum dynamics of a complete electron–nuclear wave function induced by a one-cycle IR strong attopulse and its probing by transient absorption spectroscopy using a weaker one-cycle UV attopulse.…”

Spatial and temporal control of populations, branching ratios, and electronic coherences in LiH by a single one-cycle infrared pulse

“…[61][62][63][64] The electronic states were computed at MRCI level using the quantum chemistry code MOLPRO [65], see Supplemental Materials (SM) for details. Since we report on pulses polarized along the molecular axis, we restrict the dynamics to the Σ manifold of The alternating polarity of the sequence of states implies that the Stark shifts of their potentials will be in opposite directions and this is a key to the understanding of the control and the selectivity that we report.…”