Avance 3 hd 500 wb nmr spectrometer

Solid-state NMR spectra were measured at 11.7 T using a Bruker Avance III HD 500 WB NMR spectrometer (Karlsruhe, Germany, 2013) with a 3.2 and 4 mm probe head in ZrO₂ rotors. The ¹³C MAS and CP/MAS NMR spectra employing cross-polarization (CP) were acquired using the standard pulse scheme at a spinning frequency of 5–10 kHz. The optimized recycling delay was 2 s, and the cross-polarization contact time was 2 ms. The strength of the spin-locking fields had a B1(¹³C) field nutation frequency of 62.5 kHz. The number of scans was 6–15 k. ¹H MAS NMR spectra were acquired using the standard pulse scheme with the repletion delay of 4 s and the number of scans of 4. The 2D ¹H-¹H NOESY MAS NMR correlation spectra were measured using the standard three-pulse (NOESY-type) pulse sequence at a spinning frequency of ω_r/2π = 10 kHz and recycle delay of 2 s. The t₁ evolution period consisted of 256 increments, each of 64 scans. Frictional heating of the spinning samples was compensated by active cooling, and the temperature calibration was performed with Pb(NO₃)₂.

Solid-state NMR spectra were measured at 11.7 T using a Bruker Avance III HD 500 WB NMR spectrometer (Karlsruhe, Germany, 2013) with a 3.2 or 4 mm probehead in ZrO₂ rotors. The ¹³C CP/MAS NMR spectra employing cross-polarization (CP) were acquired using the standard pulse scheme at a spinning frequency of 11 or 15 kHz. The optimized recycling delay was 6 s, and the cross-polarization contact time was 2 ms. The strength of the spin-locking fields had a B₁(¹³C) field nutation frequency of 62.5 kHz. The number of scans was 1–30 k. Single-pulse ²³Na and ³¹P MAS NMR spectra were acquired at a spinning frequency of 15 kHz with a pulse width of 1.0 μs (30° flip angle); excitation field intensity B₁(²³Na, ³¹P) of 83.3 kHz; recycle delays of 2 and 20 s, respectively; and the number of scans 64-1024 depending on the signal-to-noise ratio. Frictional heating [30 (link)] of the spinning samples was compensated by active cooling, and the temperature calibration was performed with Pb(NO₃)₂.