"High-pressure x-ray-absorption study of GaSe ",
J. Pellicer-Porres, A. Segura, Ch. Ferrer, V. Muñoz, A. San Miguel, A. Polian, J. P. Itie´, M. Gauthier and S. Pascarelli
Physical Review B 65, 174103-1-7 (2002)

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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±2 GPa, following a first-order Murnaghan equation of state with B0=92±6 GPa and B' fixed to 5. Under a plausible hypothesis, we calculate the evolution of the whole structure up to 16±2 GPa. These calculations indicate that the layer thickness decreases slightly under pressure.