Zeptosecond Birth Time Delay in Molecular Photoionization

TL;DR

This paper reveals a zeptosecond-scale delay in electron emission during molecular photoionization, showing that the electron's birth time depends on photon travel time across the molecule, demonstrated via electron interferometry.

Contribution

It introduces the concept of a zeptosecond-scale birth time delay in molecular photoionization and measures it using electron interferometry.

Findings

Delay of 247 zeptoseconds across H₂ molecule

Electron emission timing depends on photon travel time

First direct measurement of zeptosecond-scale delay

Abstract

Photoionization is one of the fundamental light-matter interaction processes in which the absorption of a photon launches the escape of an electron. The time scale of the process poses many open questions. Experiments found time delays in the attosecond ($10^{-18}$ s) domain between electron ejection from different orbitals, electronic bands, or in different directions. Here, we demonstrate that across a molecular orbital the electron is not launched at the same time. The birth time rather depends on the travel time of the photon across the molecule, which is 247 zeptoseconds ($10^{-21}$ s) for the average bond length of H$_2$. Using an electron interferometric technique, we resolve this birth time delay between electron emission from the two centers of the hydrogen molecule.