Dynamics of fluctuations below a stationary bifurcation to electroconvection in the planar nematic liquid crystal N4

We fitted $C({\bf k},\tau,\epsilon) \propto exp[-\sigma({\bf k},\epsilon)\tau]$totime-correlationfunctions$C({\bf k},\tau,\epsilon)$ of structure factors $S(\mathbf{k},t,ϵ)$ of shadowgraph images of fluctuations below a supercritical bifurcation at $V_0=V_c$ to electro-convection of a planar nematic liquid crystal in the presence of a voltage $V=\sqrt{2}{V}_{0}cos(2\pi ft)$[$\mathbf{k}=(p,q)$ is the wave vector and $ϵ\equiv V_0^2\mathrm{/}{V}_c^2-1$]. There were stationary oblique (normal) rolls at small (large) $f$. Fits of a modified Swift-Hohenberg form to $\sigma (\mathbf{k},ϵ)$ gave $f$-dependent critical behavior for the minimum decay rates ${\sigma }_0(ϵ)$ and the correlations lengths $\xi_{p,q}(\epsilon)