Non-adiabatic Coulomb effects in strong field ionisation in circularly polarised laser fields

TL;DR

This paper extends the analytical R-matrix method to include Coulomb effects in strong field ionisation by circularly polarised lasers, revealing how these effects influence ionisation dynamics and measurement calibration.

Contribution

It introduces a comprehensive analytical framework for Coulomb-corrected ionisation in circularly polarised fields, accounting for arbitrary initial angular momentum states.

Findings

Coulomb effects alter ionisation times and initial electron conditions.

Derived analytical formulas for Coulomb-corrected ionisation parameters.

Analyzed impact on attoclock calibration and orbital ionisation ratios.

Abstract

We develop the recently proposed analytical R-matrix (ARM) method to encompass strong field ionisation by circularly polarised fields, for atoms with arbitrary binding potentials. Through ARM, the effect of the potential can now be included consistently both during and after ionisation, providing a complete picture for the effects of the long-range potential. We find that the Coulomb effects modify the ionisation dynamics in several ways, including modification of (i) the ionisation (exit) times, (ii) the initial conditions for the electron continuum dynamics, (iii) the "tunnelling angle", at which the electron "enters" the barrier, and (iv) the electron drift momentum. We derive analytical expressions for the Coulomb-corrected ionisation times, initial velocities, momentum shifts and ionisation rates in circularly polarised fields, for arbitrary angular momentum of the initial state. We also analyse how the non-adiabatic Coulomb effects modify (i) the calibration of the attoclock in the angular streaking method, and (ii) the ratio of ionisation rates from $p^{-}$ and $p^{+}$ orbitals.