Experimental approaches to Heterogeneous Dynamics

International audienceDynamic heterogeneity refers to the independence of fast and slow modes in a system displaying dispersive relaxation and is not an alternative model to the dynamics in complex materials, but rather a required approach for rationalizing an increasing number of experimental results on supercooled liquids. The last twenty years has seen the advent of numerous experimental techniques aimed at studying the heterogeneous nature of viscous liquids. The methods either demonstrate heterogeneity per se, or provide information on the time‐ and length scale involved in this concept. This chapter reviews the experimental techniques that focus on molecular and polymeric glass formers, the challenges involved, and the results obtained in this relatively new field. Most approaches have particular strengths and weaknesses, so that only the synergistic efforts of combining numerous approaches will advance our understanding of the heterogeneous nature of dynamics significantly