Bruker BioSpin Solid State NMR, User Manual

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Basic Setup Procedures
User Manual Version 002 BRUKER BIOSPIN 81 (327)
With
p3
properly set, a spectrum like in
Figure 4.25.
should be obtained, with
about 93 kHz decoupling RF field.
Figure 4.25. Glycine with cw Decoupling at 90 kHz RF Field
In the spectrum above, a lorentzian deconvolution ( Analysis menu) shows a line
width of 71 Hz for the peak at 43 ppm. The line width achievable under optimum
decoupling conditions varies with the magnetic field. At fields below 9.4 Tesla
(400 MHz) this line is substantially broadened by second order quadrupolar inter-
action to
14
N. At fields above 9.4 Tesla (500 MHz and higher), the residual line
width is mostly determined by chemical shift dispersion and insufficient decou-
pling. Here less than 60 Hz (at 600 MHz) are expected. More efficient decoupling
schemes must be applied especially at higher magnetic fields. A more efficient
decoupling scheme is spinal64. Select
cpdprg2
= spinal64, set
pcpd2
to proton
180 degree pulse – 0.2 µsec for a start. A glycine spectrum as shown in
Figure
4.26.
is obtained.