236 (327) BRUKER BIOSPIN User Manual Version 002
MQ-MAS: Sensitivity Enhancement
Table 18.1. Initial Parameters for the DFS Experiment
Parameter Value Comments
pulprog mp3qdfs.av, or
mp3qdfsz.av
Pulse program.
NS 48*n (dfs)
96*n (dfsz)
Full phase cycle is important.
D0 3 µs Or longer, t
1
-period.
D1 5 * T
1
Recycle delay, use dummy scans if shorter. If d1 is too short artefacts
in the 2D spectrum may show up.
D4 20 µs Z-filter delay, mp3qdfsz.av only.
D6 see text Calculated in pulse program mp3qdfs.av only.
D10 = 4µs
D11 = 0 Used in mp3qdfs.av only.
P1 ≤ 3.6 µs Excitation pulse at pl11.
P2 see text Calculated in pulse program.
P3 20 µs 90° selective pulse at pl21 used in mp3qdfsz.av only.
P4 40 µs 180° selective pulse at pl21 used in mp3qdfs.av only.
PL1 =120 dB Not used.
PL11 Power level for excitation pulse, use value from standard MQMAS
optimization.
PL21 Power level for selective pulse, approx. pl11+30 dB taken from previ-
ous pulse calibration.
spnam1 dfs Set by AU program zg_dfs.
sp1 to be optimized Power level for dfs.
aunm zg_dfs AU program to calculate sweep.
L0 see text Fraction of rotor period for sweep.
L1 see text Number of rotor cycles for synchronization used in mp3qdfs.av only.
cnst1 see text Start frequency of sweep (in kHz).
cnst2 see text End frequency of sweep (in kHz).
cnst3 50 (in ns) timing resolution for sweep.
cnst31 “masr” Spinning frequency.
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