Measuring the photoelectron emission delay in the molecular frame

TL;DR

This paper introduces a novel method to measure photoelectron emission delays in molecules by analyzing interference patterns, enabling ultrafast timing insights without requiring attosecond experimental setups.

Contribution

A new approach to determine photoelectron emission delays from interference patterns, applicable to complex molecules and avoiding attosecond measurement challenges.

Findings

Emission delays vary significantly with emission direction.

Characteristic changes observed along the shape resonance.

Method successfully maps delays over a wide energy range.

Abstract

If matter absorbs a photon of sufficient energy it emits an electron. The question of the duration of the emission process has intrigued scientists for decades. With the advent of attosecond metrology, experiments addressing such ultrashort intervals became possible. While these types of studies require attosecond experimental precision, we present here a novel measurement approach that avoids those experimental difficulties. We instead extract the emission delay from the interference pattern generated as the emitted photoelectron is diffracted by the parent ion's potential. Targeting core electrons in CO, we measured a 2d map of photoelectron emission delays in the molecular frame over a wide range of electron energies. The measured emission times depend drastically on the emission direction and exhibit characteristic changes along the shape resonance of the molecule. Our approach can be routinely extended to other electron orbitals and more complex molecules.