4. Acquisition

Time requirement: 6.5 h Sample: 2 M sucrose in D₂O.

Record normal ¹H and ¹³C NMR spectra of the sample, note the required spectral widths and note the offset of the middle of each spectrum. Change to the 2D mode of the spectrometer and load the required pulse program. You have to set:

td2: 1 k data points in F> tdl: 2 times 512 data points in F;

sw2: 3.7 ppm sw1: 80 ppm (C,C double-quantum frequency, enter in Hz) o1: center of ¹H NMR spectrum o2: center of ¹³C NMR spectrum p1, p4, p6: 90° ¹H transmitter pulse p2, p5, p7: 180° ¹H transmitter pulse p9, p11, p13, p15: 90° ¹³C decoupler pulse p8, p10, p12, p14, p16: 180° ¹³C decoupler pulse p3: 2 ms ¹H spin-lock purging pulse dl: 1.5s d2: 1/[4(C,H)] = 1.8 ms, calculated from 'J(C,H) = 140 Hz d3: 1/[4/(C,C)] = 5 ms, calculated from'J(C,C) = 50 Hz initial value for t, evolution: 3 as increment for ¢, evolution: 1/[2-sw1] g1, g2, g3: shaped field gradients with a sinusoidal start reaching a plateau af- ter 32 data points and falling off sinusoidally with 5% truncation, 1 ms duration and ca. 0.2 T/m strength, with gradient loop counters, ring-down de- lays (200 pis), lock blanking and gradient coil blanking switches according to actual instrumentation used. Gradient strength ratio: 3.97 : -3.97 : 4.0 Decoupler attenuation and 90° pulse for GARP (19 dB, 70 μs) For the phase-sensitive echo/anti-echo scheme in F, use simultaneous data mode in F». The pulse sequence used here for the AMX spectrometer uses one scan within the go loop. The echoes (gradients: 3.97 : -3.97 : 4) and the anti-echoes (gradients: –3.97 : +3.97 : 4) are stored in different blocks. Two further loops cycle the acquisition phase and the phases of p8–p11. Thus, the result shown was obtained with 12 scans of 512

echo and 12 scans of 512 anti-echo accumulations.