Li 1s core exciton in LiH studied by x-ray Raman scattering spectroscopy.

Area of Science:

• Solid-state physics
• Materials science
• Spectroscopy

Background:

• Lithium hydride (LiH) exhibits complex electronic properties.
• Understanding core-level excitations is crucial for characterizing LiH's electronic structure.

Purpose of the Study:

• To investigate the Li 1s core excitation spectra in LiH using X-ray Raman scattering (XRS).
• To elucidate the nature of the prominent peak at the excitation onset and its contributions.

Main Methods:

• X-ray Raman scattering (XRS) spectroscopy across various momentum transfers (q).
• Ab initio calculations of XRS spectra using the Bethe-Salpeter equation (BSE).
• Real-space multiple-scattering calculations.

Main Results:

• The prominent peak at the excitation onset is attributed to both a p-type core exciton and transitions to empty conduction band states.
• This finding contrasts with previous studies attributing the feature to a single excitonic peak.
• BSE calculations confirmed the p-like angular symmetry of the core exciton and reproduced higher energy spectral features.

Conclusions:

• The electronic structure of LiH's core excitation spectra is more complex than previously understood.
• The combined experimental and theoretical approach provides a more accurate description of LiH's electronic properties.