The Eu valence in EuO under compression has been debated since the first observation of a pressure-induced isostructural volume collapse by Jayaraman five decades ago. Spectroscopic studies at the Eu $L_3$ edge suggested a valence change from divalent to trivalent due to promotion of charge from the half-filled $4f$ shell to empty $5d$ states, while density functional theory investigations have reported both support for and against such a valence change. The Eu $N_{4,5}$ edges ($4d\to 4f$ excitations) are highly sensitive to the $4f$ occupancy and thus to the Eu valence. Using x-ray Raman scattering, we measure the Eu $N_{4,5}$ edges of EuO up to 66 GPa and observe no significant change in spectral shape indicative of a modification of the $4f$ occupation. Our results therefore support a robust ${\mathrm{Eu}}^{2+}$ state across the isostructural transition at 35 GPa and the subsequent B1–B2 transition at 44 GPa.

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• Electronic structure
• High-pressure studies
• Strongly correlated systems