Figure 2. Experimental (markers) and fitted (lines) “powder-averaged”¹⁸ signal S/S₀ vs. b-value. (a) Two-compartment phantom with pure water and a concentrated solution of magnesium nitrate give rise to two isotropic Gaussian (ω-independent) components. (b) Polydomain lamellar liquid crystal giving Gaussian axial and radial diffusivities, D_A and D_R, as estimated with a “Pake” model fit¹². (c) Sediment of yeast cells with intra- and extracellular compartments, the latter exhibiting restricted (ω-dependent) diffusion.

Figure 1. Gradient waveforms g_i(t) with duration τ for comprehensive sampling of the 2D space of root-mean-square frequency ω_rms and normalized anisotropy b_Δ (“shape”) of the tensor-valued diffusion encoding spectrum b(ω) with elements b_ij(ω). The q-vector trajectories shown for the b_Δ= 0 case are derived from magic-angle spinning (MAS) and double rotation (DORn). Superquadric tensor glyphs²⁹ along the vertical axis indicate the special values b_Δ = –1/2, 0, 1/2, and 1. The waveforms are scaled to give identical b-values.