Search for acoustic and optic vibrational modes in $\mathrm{Zr_{40}Be_{60}}$ metallic glass

Dispersion of collective modes in metallic glass ($\mathrm{Zr_{40}Be_{60}}$, composed of disparate mass particles) was measured at small-angle spectrometer BRISP at the ILL what enabled us to extend to lower momentum transfers unlike to high-angle spectrometer IN4 at the ILL. It was shown that the behavior of the optical mode in the metallic glass is similar to the behavior of optic modes in the other systems with non-sized atoms (liquid LiPb, inert gas mixtures with high density ($\mathrm{He_{65}Ne_{35}}$)).