Fig. 8.

The time sequence of radio frequency (RF) pulses and pulsed field gradients (G_x, G_y and G_z along X, Y and Z-axis respectively) in filled and hatched bars respectively used in the PFG experiments to measure diffusion coefficients [85]. Thick and thin filled bars are the 180° and 90° hard pulses, respectively while the pulses marked as ‘S’ are single lobe sinc shaped pulses used to selectively invert water magnetization and of length 4 ms. The various delays used in the sequence are; τ = 0.1 ms, δ2 = 7 ms, and T = 130 ms. Gradients for the diffusion coefficient measurement (long hatched bars) are varied from 1 G cm⁻¹ to 32 G cm⁻¹ in units of 0.5 G cm⁻¹, while the other gradients (small hatched bars) are applied at a strength of 30 G cm⁻¹ for 1 ms each, yielding a total echo time (τ₁ + τ₂) of 14.026 ms. The phase cycling required to advantageously utilize the RD effects for water suppression is; ϕ₁ = 2(x), 2(y), 2(−x), 2(−y); ϕ₂ = 2(y), 2(−x), 2(−y), 2(x); ϕ₃ = −x, x, −y, y, x, −x, y, −y; ϕ₄ = 2(x), 2(y), 2(−x), 2(−y); ϕ₅ = 2(y), 2(−x), 2(−y), 2(x); ϕ₄ = 2(x), 2(y), 2(−x), 2(−y), 2(−x), 2(−y), 2(x), 2(y); receiver phase ϕ_r = −y, y, x, −x, y, −y, −x, x. Reproduced with permission from [85].