Double core hole production in N2: Beating the Auger clock

TL;DR

This study demonstrates the creation of double K-shell holes in N2 molecules using intense x-ray pulses, revealing new insights into molecular core-hole states and their decay processes.

Contribution

First direct observation of same-atom double core holes in a molecule, advancing understanding of ultrafast core-hole dynamics.

Findings

First direct detection of same-atom double core holes in N2

Good agreement between experimental results and theoretical predictions

Established an upper bound for different-atom double core hole contribution

Abstract

We investigate the creation of double K-shell holes in N2 molecules via sequential absorption of two photons on a timescale shorter than the core-hole lifetime by using intense x-ray pulses from the Linac Coherent Light Source free electron laser. The production and decay of these states is characterized by photoelectron spectroscopy and Auger electron spectroscopy. In molecules, two types of double core holes are expected, the first with two core holes on the same N atom, and the second with one core hole on each N atom. We report the first direct observations of the former type of core hole in a molecule, in good agreement with theory, and provide an experimental upper bound for the relative contribution of the latter type.