Dynamical symmetry breaking under core excitation in graphite: Polarization correlation in soft X-ray recombination emission

TL;DR

This study uses recombination emission spectroscopy to reveal local lattice distortions and symmetry breaking in graphite caused by core excitation, supported by theoretical modeling.

Contribution

It demonstrates the first direct observation of dynamical symmetry breaking under core excitation in graphite through polarization correlation analysis.

Findings

Recombination emission spectrum shows a low-energy tail indicating lattice distortion.

Theoretical calculations reproduce experimental spectral features.

Strong polarization correlation evidences symmetry breaking in core exciton state.

Abstract

A recombination emission spectrum is applied to study the local lattice distortion due to core excitation in graphite. The recombination emission spectrum reveals a long low-energy tail when the C $1s$ electron is excited to the $\sigma^*$ core exciton state. This indicates a large local lattice distortion around the excited carbon atom within a core hole lifetime ($\sim$10fs). Theoretical calculation based upon an ionic cluster model well reproduces the experiments. The strong polarization correlation between incident and emitted X-rays is conclusive evidence of symmetry breaking in the core exciton state due to coupling with asymmetric vibrational modes.