Wave-vector dependence of dynamics in deeply undercooled metallic melts

X-ray Photon Correlation Spectroscopy (XPCS) is the only technique able to probe the slow atomic motion of glasses. Here, we aim to take advantage from the 30x increase in coherent flux of ID10 beamline at ESRF-EBS, to probe the wave vector dependence of the dynamics of metallic glass formers across the glass transition and in a previously unexplored spatial range, covering two orders of magnitude in wave vectors, Qs, from the macroscopic limit down to the atomic scale. From the Q-dependence of the structural relaxation time, τ(Q), and of the shape parameter, β(Q), of the long-time decay of the intermediate scattering function (ISF) we will be able to unveil the mechanism responsible for particle motion across the glass transition and to compare it with results from recent numerical simulations and theoretical studies.