Viscoelasticity of 2D Liquids Quantified in a Dusty Plasma Experiment

The viscoelasticity of two-dimensional liquids is quantified in an experiment using a dusty plasma. An xperimental method is demonstrated for measuring the wave-number-dependent viscosity eta(k), which is a quantitative indicator of viscoelasticity. Using an expression generalized here to include friction, eta(k) is computed from the transverse current autocorrelation function, which is found by tracking random particle motion. The transverse current autocorrelation function exhibits an oscillation that is a signature of elastic contributions to viscoelasticity. Simulations of a Yukawa liquid are consistent with the experiment.