Figure 5.

94 GHz ¹⁹F Mims ENDOR spectra of F₃Y₁₂₂-β₂/F₂Y₇₃₁-α₂ (80 μM, T_Q = 50 s, black lines) and E₅₂Q/F₃Y₁₂₂-β₂/F₂Y₇₃₁-α₂ (80 μM, T_Q = 35 s, red lines) at T = 50 K. Spectra in panels (A) and (B) were obtained by adding three orientation-selective spectra. (A) Measurement with short τ values (∼250 ns). (B) Measurement with larger τ values (∼620 ns). (C) Orientation-selective spectra with B₀ a∥ g_x and τ = 620 ns after data point smoothing with the Savitzky–Golay filter (full lines). Original data are shown as dotted lines. Measurement time per spectrum is 30–40 h (A) and 50–60 h (B). Analysis of the spectra in panels (A)–(C) requires consideration of four nuclei ¹⁹F_a–¹⁹F_d, as marked by arrows and colored dashed lines.