Multielectron effects in strong field ionization of CO$_2$: impact on differential photoelectron spectra

TL;DR

This study provides detailed photoelectron spectra from CO$_2$ using ab initio methods, revealing significant excited state contributions and their effects on spectral features across different laser wavelengths and molecular orientations.

Contribution

It introduces a comprehensive ab initio coupled channels approach to analyze multielectron effects in strong field ionization of CO$_2$, highlighting the role of excited states.

Findings

Excited state channels can dominate over ground state in certain orientations.

Ionization to excited states causes partial washout of multiphoton and nodal structures.

Spectral features are influenced by ionization thresholds, orbital symmetries, and interchannel coupling.

Abstract

We report fully differential photoelectron spectra from an {\it ab-inito} coupled channels treatment of CO$_2$. Photoionization by laser pulses centered at 400 nm and 800 nm wavelength are considered, with arbitrary molecular alignment and polarization (linear and elliptic). Calculations reveal significant excited state channel contributions that are, at certain molecular orientations, an order of magnitude larger than the ground state channel in the rescattering plateau. Partial wash out of the multiphoton structure in the ATI spectra and of the nodal features in angle resolved spectra is observed due to ionization to excited state channels. The qualitative nature of the spectra is determined by ionization thresholds, orbital symmetries and interchannel coupling in the order of precedence.