Low-frequency Raman scattering under high pressure in diamond anvil cell: Experimental protocol and application to GeO2 and SiO2 boson peaks

► An experimental protocol is proposed to obtain high quality low-frequency Raman spectra under high pressure. ► We show that the evolution of the boson peak of strong glasses under pressure is correlated to the evolution of the shear modulus. ► Applying pressure leads to a gradual homogenisation of glasses at the nanometre scale. ► A reversible polyamorphic transition explains the observed results.