248 (327) BRUKER BIOSPIN User Manual Version 002
STMAS
ph1 = 0 2
ph2 = 0 0 2 2
ph3 = 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3
ph4 = 0*8 1*8 2*8 3*8 4*8
receiver = 0 2 2 0 2 0 0 2 0 2 2 0 2 0 0 2 1 3 3 1 3 1 1 3 1 3 3 1 3 1 1 3
2 0 0 2 0 2 2 0 2 0 0 2 0 2 2 0 3 1 1 3 1 3 3 1 3 1 1 3 1 3 3 1.
In the stmasdqfz.av pulse sequence this pulse flips the magnetization back along
the z-axis. After a short z-filter delay D4 a CT selective 90° pulse P3 creates
transverse magnetization. In the stmasdqfe.av pulse sequence the non-selective
pulse P2 converts the ST SQ coherence into CT SQ coherence. This is allowed to
evolve for another delay D6 after which it refocuses into an echo by a CT selective
180° pulse. When either the D6 before the 180° pulse or D7 after the 180° pulse is
incremented proportionally to the t
1
period a split-t
1
experiment as described in
chapters 16 and 17 for some MQMAS experiments will be performed.
Figure 19.3. Four pulse sequence and coherence transfer pathway
Four pulse sequence and coherence transfer pathway for the double quantum fil-
tered STMAS experiment with shifted echo acquisition (stmasdqfe.av). Pulses p1
and P2 are non-selective pulses. Corresponding power level PL11 should be set
to achieve around 100 kHz RF field amplitude. P3 and P4 are CT selective pulse
90° and 180° pulses of about 20 and 40 µs, respectively, corresponding to an RF
field amplitude of a few kHz. Delay D0 is the incremented delay for t
1
evolution,
D6 and D7 can be incremented proportional to D0 depending on the spin of the
observed nucleus. Phase lists are as follows, incrementation of the phase of the
first pulse is not required because a phase modulated data set is acquired with
FnMODE being QF:
ph1 = 0 180 90 270
ph2 = 0*4 90*4 180*4 270*4
ph3 = 0*16 90*16 180*16 270*16
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