Electronic coherences in nonadiabatic molecular photophysics revealed by time-resolved photoelectron spectroscopy

Abstract

Significance Time-resolved photoelectron spectroscopy (TRPES) is a promising technique for the study of ultrafast molecular processes, such as the nonadiabatic dynamics taking place at conical intersections. Directly accessing the evolution of the coherences generated at the conical intersection should provide most valuable dynamical information. However, the signals are dominated by background contributions due to state populations, and most theoretical treatments completely neglect the role of the coherences. Here we show that distinguishable signatures of molecular coherences appear in TRPES. These can be recorded using currently available ultrashort pulses and unambiguously extracted at the postprocessing stage. The technique thus provides direct access to nonadiabatic coherence dynamics.

Trends in angle-resolved molecular photoelectron spectroscopy

“…[447][448][449] Despite the popularity of challenging pump-probe experiments, quite few probe the dynamics beyond the simple photoelectron spectra, often leading to a limited characterization of the internal dynamics, with remaining ambiguities. The rich information embodied in angularly resolved studies from oriented molecules will be greatly beneficial to fully characterize the electronic states involved, their coupling with nuclear motion, 450 and the electron wavepacket coherences 395,451,452 and bifurcations, up to now quite elusive, both in valence excitation and ionization with broad pulses.…”

Ultrafast Imaging of the Jahn–Teller Topography in Carbon Tetrachloride

“…More recent efforts in experimental and theoretical studies of PESs within molecular sciences have been focused on dynamics at conical intersections (CIs). − These topographical features are highly efficient at converting potential energy into kinetic energy without radiative losses . For example, in nature, many essential biological photoreactions have evolved to proceed via CIs as a result of this energy efficiency, , and their role in energy and charge transfer reactions is a topic of great current interest. − CIs additionally form in the intersections between electronic states in spontaneous symmetry-breaking processes, such as in Jahn–Teller active systems. − This effect can be observed spectroscopically in any system that exhibits degeneracy due to symmetry.…”

Time-resolved X-ray and XUV based spectroscopic methods for nonadiabatic processes in photochemistry

“…54–56 Besides X-ray based methods, time-resolved photoelectron spectroscopy (TRPES) has been shown capable of observing the population transfer and studying the electronic coherence created in the vicinity of a CI. 57–60…”

“…[54][55][56] Besides X-ray based methods, time-resolved photoelectron spectroscopy (TRPES) has been shown capable of observing the population transfer and studying the electronic coherence created in the vicinity of a CI. [57][58][59][60] In this feature article, we want to give an overview of these novel time-resolved spectroscopic techniques that can be used to study dynamics in the vicinity of CI. After giving a brief…”

“…Time-resolved X-ray diffraction (XRD) has been implemented to spatially detect the occurrence of nonadiabatic dynamics in a molecule [54][55][56]. Besides X-ray based methods, time-resolved photoelectron spectroscopy (TRPES) have been shown capable of observing the population transfer and studying the electronic coherence created in the vicinity of a CI [57][58][59][60].…”