(A) Calculated MAS-DNP polarization gain, ϵB, for a Trityl-nitroxide biradical using the modified Box model, with μw irradiation (red squares), and without (black dots) as a function of the nitroxide hyperpolarization. (B) Calculated ∣ϵB∣ as function of magnetic field without μw irradiation, assuming a nitroxide hyperpolarization of Pe,a → −0.75 at 100 K (black dots) and 200 K (red squares). All other simulation parameters were kept constant. Dashed lines: best fits using Eq. (5).