High-pressure x-ray-absorption study of GaSe

Abstract

We performed two x-ray-absorption experiments under pressure in GaSe, at the Ga and Se K edges (10.368 and 12.653 keV, respectively), up to 34 GPa. The Ga-Se distance obtained from the extended x-ray-absorption fine-structure fit decreases monotonically up to $16\ifmmode\pm\else\textpm\fi{}2\mathrm{GPa},$ following a first-order Murnaghan equation of state with ${B}_{0}=92\ifmmode\pm\else\textpm\fi{}6\mathrm{GPa}$ and ${B}_{0}^{\ensuremath{'}}$ fixed to 5. Under a plausible hypothesis, we calculate the evolution of the whole structure up to $16\ifmmode\pm\else\textpm\fi{}2\mathrm{GPa}.$ These calculations indicate that the layer thickness decreases slightly under pressure.