Figure 2.

Gradient trajectories for angular d-PFG (left) and sd-PFG (right) in q_s, q_d and q₁, q₂ coordinates, this varies the relative magnitudes of q_s and q_d and so modulates the measurement's sensitivity to D̄_Δ and D̄_2Δ. sd-PFG modulates the relative amplitudes of q₁ and q₂, but never orientation, in a manner so to fix the corresponding magnitudes of q_s and q_d for a constant relative sensitivity to D̄_Δ and D̄_2Δ