Bulk electronic structure ofK3C60as revealed by soft x-rays

Abstract

We present $\mathrm{C}\phantom{\rule{0.2em}{0ex}}1s$ x-ray absorption, x-ray emission, and resonant inelastic x-ray scattering (RIXS) spectra of single-phase crystalline ${\mathrm{K}}_{3}{\mathrm{C}}_{60}$. The comparison to valence-band photoelectron spectra from the same sample facilitates identification of the contribution from surface and bulk electronic states in the latter. Bulk-sensitive techniques show that the valence bands of ${\mathrm{K}}_{3}{\mathrm{C}}_{60}$ and pure ${\mathrm{C}}_{60}$ are characterized by spectral features of similar width, in agreement with the predictions of band-structure calculations. Symmetry selectivity in the RIXS process allows us to assign peaks in the $\mathrm{C}\phantom{\rule{0.2em}{0ex}}1s$ absorption spectrum, demonstrating a close correspondence with pure ${\mathrm{C}}_{60}$ also in the conduction band. The symmetry selectivity is as pronounced in ${\mathrm{K}}_{3}{\mathrm{C}}_{60}$ as in pure ${\mathrm{C}}_{60}$, indicating that the local ${\mathrm{C}}_{60}$ symmetry is not appreciably affected by the K doping, either in the ground state or intermediate state, on the time scale of $6\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$.