Figure 2.

Comparison of 1D ¹³C spectra of (a) hβ₂m and (b) ΔN6 fibrils at 313 K using cross-polarization (CP, top), direct polarization (DP, middle) and INEPT (bottom). In the case of ΔN6 we superimposed the traces from DP (red) and CP (black) to illustrate that the spectral features are largely preserved. The intensities were scaled to match in the alphatic region. Each CP and DP spectrum was recorded with 16 scans, while each INEPT spectrum required 64 scans. All spectra were collected at 13 kHz MAS frequency, 100 kHz ¹H TPPM decoupling, and at 800 MHz ¹H frequency. The ¹H–¹³C CP contact time was ∼1.5 ms, and the recycle delay for the DP and INEPT spectra was 5–5.5 s.