Fig. 4
From: Morphing of liquid crystal surfaces by emergent collectivity
Frequency-resolved analysis of morphing kinetics. a Spectrogram of the dynamics after field switch-on at Δt = 0. Each horizontal strip represents one power spectrum of the temporal speckle intensity, averaged over 0.015 mm2 surface. Three distinct dynamic stages can be identified. The colour scale ranges from −3 to −0.1. b Illustration of the field-off steady state (top) and morphing stages. Only the inter-electrode region is drawn. (I) Dielectric interactions drive the polar mesogens to oscillate along the AC field lines. (II) Under resonance conditions, the pendant and crosslink mesogens start moving cooperatively and plasticize the network. (III) A feedback loop of network weakening and increased oscillation amplitude causes amplification of the free volume, culminating in microscopic expansion. c Power spectra matching the indicated cross-sections in a. All stages exhibit high-frequency motions that are ballistic in nature i.e. characterized by power law −2. By contrast, a static reference sample (blue line) obeys a complex f-dependence dominated by low modes, due to external noise rather than intrinsic material properties
