FIG. 8.

Normalized simulations of the DNP field profiles for SA-BDPA and BDPA at (a) 9.4 and (c) 14.1 T and (b) for d₂₁-BDPA at 9.4 T at T = 100 K assuming (ω_1S/2π)∼0.85 MHz. The following parameters were used in the simulations: BDPA:A_iso = 2.5 MHz, A_dip = 1.5 MHz (in the principal axis frame), is the same order of magnitude as the published data.^41,42 We employed an average value of the isotropic hyperfine value. ${\Gamma }_{1,ZQ}={\left(T_1^{ZQ}\right)}^{-1}=0.91s^{-1}$, ${\Gamma }_{1,DQ}={\left(T_1^{DQ}\right)}^{-1}=0.40s^{-1}$, Γ_1n = (T_1n)⁻¹ = 0.16 s⁻¹ @ 9 T and 14 T, SA-BDPA:A_iso = 2 MHz, A_dip = 1.5 MHz (in the principal axis frame), assuming the sulfonation may affect the isotropic values by reducing the number of protons on the rings. ${\Gamma }_{1,ZQ}={\left(T_1^{ZQ}\right)}^{-1}=0.24s^{-1}$, ${\Gamma }_{1,DQ}={\left(T_1^{DQ}\right)}^{-1}=0.18s^{-1}$, Γ_1n = (T_1n)⁻¹ = 0.03 s⁻¹ @ 9 T and Γ_1n = (T_1n)⁻¹ = 0.02 s⁻¹ @ 14 T. d₂₁-BDPA: A purely dipolar coupling of 0.1 MHz which corresponds to e⁻-¹H distance of 0.9 nm, and cross relaxation rates ${\Gamma }_{1,ZQ}={\left(T_1^{ZQ}\right)}^{-1}=0.001s^{-1}$, ${\Gamma }_{1,DQ}={\left(T_1^{DQ}\right)}^{-1}=0.003s^{-1}$ were used.