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MQ-MAS: Sensitivity Enhancement
User Manual Version 002
BRUKER BIOSPIN
233 (327)
Figure 18.2. Processing of Hahn Echo. Left is the Shifted Echo.
The middle shows the spectrum after FT. On the right is the spectrum with the cor-
rect first order phase correction.
Implementation of DFS into MQMAS Experiments
18.2
Two pulse sequences are available to implement a double frequency sweep
(DFS).
shows the 4-pulse sequence with z-filter,
mp3qdfsz.av
. The
principle of this sequence is already described in the chapter
, with a CW pulse instead of a DFS for conversion.
shows a 3-pulse sequence with a shifted echo acquisition in a split-t
1
experiment,
mp3qdfs.av
. In both sequences the same sweep is used. Both sequences start
with an excitation pulse
p1
that creates 3Q coherence which is allowed to evolve
during the evolution period
D0
. The sweep during
P2
is used to change (non-ob-
servable) 3Q coherency to observable SQ coherency. In the 4-pulse sequence
they pass through a z-filter by a sequence of CT selective 90°-90° pulses
P3-D4-
P3
. In the 3-pulse sequence a delay
D6
is introduced so that the obtained signal
can first dephase and then be refocused with a 180° CT selective pulse.
Optimization of the Double Frequency Sweep (DFS)
18.2.1
At this point it is assumed that the pulses
p1
,
P3
, and
P4
together with their corre-
sponding power levels
PL11
and
PL21
are already calibrated as described in the
chapter
. Starting from this set-up a data set
should be created into which either of the two DFS pulse programs is loaded.
Содержание Solid State NMR
Страница 1: ...Version Bruker BioSpin think forward NMR Spectroscopy Solid State NMR 002 AVANCE Solids User Manual...
Страница 8: ...8 BRUKER BIOSPIN User Manual Version 002 Contents...
Страница 14: ...14 327 BRUKER BIOSPIN User Manual Version 002 Test Samples...
Страница 104: ...104 327 BRUKER BIOSPIN User Manual Version 002 Practical CP MAS Spectroscopy on Spin 1 2 Nuclei...
Страница 118: ...118 327 BRUKER BIOSPIN User Manual Version 002 Basic CP MAS Experiments...
Страница 122: ...122 327 BRUKER BIOSPIN User Manual Version 002 FSLG HETCOR Figure 8 3 The ased Display...
Страница 154: ...154 327 BRUKER BIOSPIN User Manual Version 002 Proton Driven Spin Diffusion PDSD...
Страница 172: ...172 327 BRUKER BIOSPIN User Manual Version 002 SUPER Figure 13 3 The Acquisition Parameter Window eda...
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