Figure 5.

Pulse scheme for the measurement of R₂ and R₁ relaxation rates of the outer ¹³C magnetization modes of the I = 3/2 manifold (L₁ ± L₄) in ¹³CH₃ methyl groups. All the parameters of the scheme (including delays) are the same as described in Figure 2. The ¹H pulse shown in blue is applied with the flip-angle β = cos⁻¹(1/√3) = 54.7°. “Open” ¹H pulses in R₂ measurements are composite pulses of the 90°–240°–90° variety²⁹ that are applied with the phase-cycling indicated in the figure. Only the scheme for in-phase (L₁ + L₄) R₁ measurements is shown as used in practice. The durations and strengths of the pulsed-field gradients(ms; G/cm) are as follows: g1 = (1; 25), g2 = (0.4; 15), g3 = (0.3; 12), g4 = (0.35; 12), g5 = (0.4; 15), g′ = (1.2; 20), g″ = (0.8; 15), g‴ = (0.8; 20), and g⁗ = (0.6; 20). The phase cycle is as follows: ϕ1 = 2(x), 2(−x); ϕ2 = x, −x; ϕ3 = 4(x), 4(−x); ϕ4 = x, −x; ϕ5 = 4(x), 4(−x); ϕ′ = 4(x), 4(−x); and = receiver phase of (x,−x,−x,x, −x,x,x,−x). Quadrature detection in t₁ is achieved via States-TPPI²⁸ incrementation of ϕ4.