Figure 6.

Measured (black solid line) and simulated (red dashed line) CP-detection nutation spectra at 20 kHz MAS obtained in the 3.2 mm probe (top) and in the 1.6 mm probe (bottom), by applying CP without a ramp (left) or with a ±10% ramp on the X channel (right). The detected molecular sites are ¹³Cα in alanine (a, b), ¹³Cα of Met in MLF (c), and ¹⁵N in NAV (d). In the simulations, ${\nu }_{1H}^{\mathit{cent}}$ and ${\nu }_{1X}^{\mathit{cent}}$ of the CP irradiation were 70 and 46 kHz (a), 70 and 45.5 kHz (b), 90 and 64 kHz (c), and 73 and 50 kHz (d), respectively. The CP contact time was 1 ms (a, b, c) or 1.5 ms (d).