Microscopic dynamics in the glass former B2O3 measured by X-ray photon correlation

Despite the strong efforts carried out over the last decades, a microscopic description of the glassy state is still missing. One of the main obstacles to advance in the field arises from the difficulty of achieving information on the dynamics at the atomic scale. Here we exploit the unique characteristics offered by X-ray photon correlation to directly observe the dynamics at the microscopic length-scale in the strong glass former B2O3. In the supercooled liquid phase, the microscopic dynamics is more than a decade faster than that measured with macroscopic techniques, as already observed in other systems. Surprisingly, instead, the microscopic dynamics is not frozen in the glassy state: it remains of the order of 100 s, with slight temperature dependence below the glass transition.