# Attosecond delays in laser-assisted photodetachment from closed-shell negative ions

## TL;DR

This paper investigates attosecond laser-assisted photodetachment delays in negative ions, revealing how short-range potentials significantly influence measured delays, especially at low energies, challenging the assumption of delay universality.

## Contribution

It provides a detailed analysis of delay contributions in negative ions and demonstrates the impact of short-range potentials on delay measurements, which was previously underestimated.

## Key findings

- Delay contributions are negligible at high energies due to asymptotic behavior.
- Significant deviations occur at low photoelectron energies.
- Short-range potentials can induce delays up to 50 attoseconds.

## Abstract

We study laser-assisted photodetachment time delays by attosecond pulse trains from the closed-shell negative ions F- and Cl-. We investigate the separability of the delay into two contributions: (i) the Wigner-like delay associated with one-photon ionization by the attosecond pulse train and (ii) the delay associated with exchange of an additional laser photon in the presence of the potential of the remaining target. Based on the asymptotic form of the wave packet, the latter term is expected to be negligible because the ion is neutralized leading to a vanishing laser-ion interaction with increasing electron-atom separation. While this asymptotic behavior is verified at high photoelectron energies, we also quantify sharp deviations at low photoelectron energies. Further, these low-energy delays are clearly different for the two studied anions indicating a breakdown of the universality of laser-ion induced delays. The fact that the short-range potential can induce a delay of as much as 50 as can have implications for the interpretation of delay measurements also in other systems that lack long-range potential.