Dynamical Symmetry Breaking under Core Excitation in Graphite: Polarization Correlation in Soft X-Ray Recombination Emission

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 σ * core exciton state. This indicates a large local lattice distortion around the excited carbon atom within a core hole lifetime (∼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. * Electronic address:

Resonant inelastic X-ray scattering at the Be 1s edge in BeO

“…Unlike photoelectron spectroscopies it is non-sensitive to sample charging, and is particularly useful for crystalline bulk insulator studies for materials, like BeO, which are not easily obtained as thin films without serious stoichiometry issues. A few recent RIXS studies [1,2] are closely related to this present work. Ma et al [1] observed the long energy loss tail to the elastic scattering peak, while in the absorption spectrum only a relatively sharp core exciton peak was observed.…”

“…[2,4]. When the excitation energy is increased even further and reaches values of approximately 130 eV, a satellite band, similar to the LET, appears again to the off-resonant X-ray emission spectra, although its intensity then is substantially weaker.…”

“…A similar phenomenon is typical of valence excitons in alkali halides and in oxides, where self-trapping of valence excitons occurs in the course of lattice relaxation, and the radiation emitted during the lattice relaxation process has been called "hot luminescence". The term hot luminescence has even been introduced to describe the processes related to the appearance of the energy loss side-band of the elastic peak in RIXS spectra [2,3]. Recently a similar side-band has been observed in the RIXS spectra of LiNO 3 [4], where it was attributed to the dynamics of X-ray emission, accompanying the distortion of NO 3 − species.…”

Resonant inelastic x-ray scattering and UV–VUV luminescence at the Be 1s edge in BeO

“…A few RIXS studies [4,5] are closely related to the present work. Ma et al [4] observed the long energy loss tail to the elastic scattering peak, while in the absorption spectrum only a relatively sharp core exciton peak was observed.…”

“…Two kinds of selftrapped excitons (STE) have been identified-excitons with axial localization of the hole component (STE1) and excitons 5 Deceased.…”