Response time of electron inside a molecule to light in strong-field ionization

TL;DR

This paper investigates the electron response time during strong-field ionization of molecules versus atoms, revealing a longer tunneling time for molecules, influenced by molecular structure and internuclear distance.

Contribution

It introduces a combined numerical and analytical model that accurately predicts the electron response time difference between molecules and atoms in strong laser fields.

Findings

Molecular ionization exhibits a larger offset angle than atomic ionization.

Electron response time is approximately 15 attoseconds longer in molecules.

Increasing internuclear distance further prolongs the electron response time.

Abstract

We study ionization of aligned H$_2^+$ in strong elliptically-polarized laser fields numerically and analytically. The calculated offset angle in photoelectron momentum distribution is several degrees larger for the molecule than a model atom with similar ionization potential at diverse laser parameters. Using a strong-field model that considers the properties of multi-center and single-center Coulomb potentials, we are able to quantitatively reproduce this angle difference between the molecule and the atom. Further analyses based on this model show that the response time of electron to light which is encoded in the offset angle and is manifested as the time spent in tunneling ionization, is about 15 attoseconds longer for the molecule than the atom. This time difference is further enlarged when increasing the internuclear distance of the molecule.