FIG. 5.

Optimization of the NOVEL pulse sequence in DPNO/BzP. (a) The signal intensity increases quickly after τ_mix ∼ 100 ns and exhibits a transient oscillation. Both features are consistent with the electron-¹H dipolar coupling in the order of 1-10 MHz. Optimization in terms of the repetition time (essentially τ₁) at 270 K (b) and 150 K (c) with different mixing times. At 270 K, we observed mostly the decay of the signal with respect to the repetition time. At 150 K, the signal intensity reached the maxima at ∼130 μs of repetition time.