Direct measurement of the structural change associated with amorphous solidification using static scattering of coherent radiation.

• DOI: 10.48550/arxiv.2302.11872
• Publication Date: 2023-12-28
• Authors: Charlotte F. Pete...; Peter Harrowell
• Keywords: Condensed Matter - Materials Science; 0103 physical sciences; Materials Science (cond-mat.mtrl-sci); Soft Condensed Matter (cond-mat.soft); FOS: Physical sciences; Condensed Matter - Soft Condensed Matter; 530; 01 natural sciences; 620

In this paper, we demonstrate that the weak temperature dependence of the structure factor of supercooled liquids, a defining feature of the glass transition, is a consequence of the averaging of the scattering intensity due to angular averaging. We show that the speckle at individual wavevectors, calculated from a simulated glass former, exhibits a Debye–Waller factor with a sufficiently large temperature dependence to represent a structural order parameter capable of distinguishing liquid from glass. We also extract from the speckle intensities a quantity proportional to the variance of the local restraint, i.e., a direct experimental measure of the amplitude of structural heterogeneity.