Figure 3.
Offset dependence of the Rex contribution to R1ρ for linear three-site exchange for varying major populations in the weak field limit (pA = 0.94, pA = 0.85, pA = 0.7 and pA = 0.52, as indicated). (Solid) Numerical calculation of Rex = −λ/sin2 θ from the least negative real eigenvalue of the 9 × 9 evolution matrix, (dashed) calculation from the first-order approximation from Eq. 11, and (dotted) calculation from the second-order approximation from Eqs. 29 and 40. The inset exemplifies a region in which the results of the calculations differ. To center the graph, parameters were chosen so that δA = ΔΩ. Parameters used for the calculations were pB = 2(1− pA)/3, pC = (1−pA)/3, k12+k21 = 50 s−1, k13 +k31 = 100 s−1, ω1 = 50 s−1, ΩB − ΩA = 200 s−1, and ΩC − ΩA = −400 s−1.