Catching the geometric phase effect around conical intersection in molecules by high order harmonic spectroscopy

TL;DR

This paper demonstrates how high-order harmonic spectroscopy can detect the geometric phase effects around conical intersections in molecules, revealing distinct spectral behaviors compared to avoided crossings and enabling sub-femtosecond resolution of molecular dynamics.

Contribution

It shows that geometric phase effects at conical intersections influence high-order harmonic spectra, providing a new spectroscopic method to study ultrafast molecular nonadiabatic dynamics.

Findings

Oscillatory spectral behavior due to avoided crossing coherence

Erosion of oscillations by geometric phase at conical intersections

Sub-femtosecond resolution of molecular dynamics through spectral shifts

Abstract

Nonadiabatic dynamics around an avoid crossing or a conical intersection play a crucial role in the photoinduced processes of most polyatomic molecules. The present work shows that the topological phase in conical intersection makes the behavior of pump-probe high-order harmonic spectroscopy different from the case of avoid crossing. The coherence built up when the system crosses the avoid crossing will lead to the oscillatory behavior of the spectrum, while the geometric phase erodes these oscillations in the case of conical intersection. Additionally, the dynamical blueshift and the splitting of time-resolved spectrum allow capturing the snapshot dynamics with sub-femtosecond resolution.