Activated Relaxation and Transport in Liquids Well Above T_m

Microscopic molecular theories of supercooled liquids and glasses often posit the presence of long-lived structures in these systems. Such structures are required to produce observed phenomenology such as spatially heterogeneous dynamics. We find evidence for such structures not only in supercooled liquids, but in simple liquids far above the melting temperature. We present neutron scattering [1, 2], simulation [3], and ultrafast optical experiments showing that these structures and associated dynamic heterogeneities arise at much higher temperature than is typically expected. We also show that they play a very important role in overall transport and relaxation, even in the liquid state.

[1] Cicerone et al., Physical Review Letters, 113:11, 117801 (2014)
[2] Cicerone et al., The Journal of Chemical Physics 146:5, 054502 (2017)
[3] Cicerone et al., Journal of Non-Crystalline Solids 407, 118-125 (2015)