4. Acquisition

Time requirement: 30 min Sample: Fill a solid-state rotor with finely powdered glycine.

Load standard ¹³C NMR parameters. You have to set:

td: 4k sw: 500 ppm o1: middle of ¹³C NMR spectrum o2: middle of ¹H NMR spectrum p1: 90° ¹H decoupler pulse p2: 5 ms ¹H spin-lock decoupler pulse p3: 5 ms ¹³C spin-lock transmitter pulse dl:3s decoupler attenuation for cross-polarization decoupler attenuation for high-power cw decoupling, typically 2 dB less than for cross-polarization; on instruments with no fast power switching use same attenuation as for cross-polarization rg: receiver gain for correct ADC input spinning rate vp a: 5000 Hz, b: 4000 Hz, e: 3000 Hz, d: 2000 Hz, e: 1000 Hz, f: 500 Hz, g: 0 Hz ns: 16 in Experiments a to c, 64 in d to f, and 256 in g

5. Processing

Use standard 1D processing for ¹³C NMR as described in Experiment 3.2 with zero-filling to 4 k and different exponential multiplication corresponding to the line-width, ranging from lb = 25 Hz in a to lb = 100 Hz ing.

6. Result

The figure shows the spectra of glycine obtained using a multinuclear solid-state probe-head with a 7 mm rotor on an AM-400 spectrometer with wide-bore magnet. As can be seen from the figure, signals of nuclei with large chemical-shift anisotropy such as the signal from the carboxyl ¹³C nucleus, generate spinning side-bands; at low spinning speed the signal of the methylene ¹³C nucleus also yields side-bands. The spinning rate can be measured from the distance of the spinning side-bands and the side- band pattern can be analyzed to obtain the chemical-shift tensor [4].