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Résumé:

We investigate vitreous silica pressurized under the noble gases, He, Ne and Ar by both spectroscopic techniques and numerical simulations. We find an unexpectedhuge solubility of He and Ne at high pressure together with a large decrease of the static compressibility. We show that this relates to the open and flexible structure of the glass allowing gas atoms to distend the network, the same way a porous material deform upon fluid adsorption. This behavior can be rationalized using generalized poromechanical constitutive equations. Direct optical microscopy observations highlight the swelling of the silica network upon fluid adsorption. Very sharp diffusion front of the fluid into the silica the sample is further observed indicating non trivial kinetics of the diffusing atoms. In the Ne case, adsorption-desorption kinetics canbe tracked by Brillouin spectroscopy.