The influence of final state interactions in attosecond photoelectron interferometry

TL;DR

This paper investigates how final state interactions affect attosecond photoelectron interferometry measurements near Fano resonances in argon, revealing the influence of two-photon transition interactions on phase measurements.

Contribution

It demonstrates the impact of final state interactions on phase measurements in attosecond interferometry near Fano resonances using high-resolution techniques and theoretical calculations.

Findings

Phase varies across the resonance depending on experimental conditions.

Final state interactions influence the measured phase.

Theoretical models confirm the role of two-photon transition interactions.

Abstract

Fano resonances are ubiquitous phenomena appearing in many fields of physics, e.g. atomic or molecular photoionization, or electron transport in quantum dots. Recently, attosecond interferometric techniques have been used to measure the amplitude and phase of photoelectron wavepackets close to Fano resonances in argon and helium, allowing for the retrieval of the temporal dynamics of the photoionization process. In this work, we study the photoionization of argon atoms close to the $3s^13p^64p$ autoionizing state using an interferometric technique with high spectral resolution. The phase shows a monotonic $2{\pi}$ increase across the resonance or a sigmo\"idal less than ${\pi}$ variation depending on experimental conditions, e.g. the probe laser bandwidth. Using three different, state-of-the-art calculations, we show that the measured phase is influenced by the interaction between final states reached by two-photon transitions.