W L3-edge x-ray study of 5d orbital excitations in WSe2 and WTe2

초록

Two tungsten-based transition metal dichalcogenides (TMDs), tungsten diselenide (WSe2) and ditelluride (WTe2), offer suitable model systems for investigating the interplay between crystal structures and 5d-orbital hybridization in layered transition-metal systems. Using W L3-edge x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS), we directly investigate the W 5d electronic states in polycrystalline TMDs samples. Combined with structural analyses, the white-line peaks in the XAS spectra, examined by their first-derivative peak positions, indicate symmetry-driven orbital states of WSe2 and WTe2. The corresponding RIXS spectra exhibit clearly distinct dd-excitations, indicating differences in W 5d orbital occupancy and ligand hybridization between the two compounds. This study provides a spectroscopic framework for understanding electronic structures of tungsten dichalcogenides in relation to chalcogen coordination changes and their topological and catalytic properties.

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