222 (327) BRUKER BIOSPIN User Manual Version 002
Basic MQ-MAS
Data processing 17.4
Processing parameters should be set according to the following table:
Data obtained with mp3qzfil.av from nuclei with spin I = 3/2 can be processed with
xfb, if IN10 has been set appropriately to run a split-t
1
experiment. If this is not the
case data can be sheared in order to align the anisotropic axis along the F2 axis.
This is done with the AU program xfshear. The AU program checks the nucleus
to determine the spin quantum number, checks the name of the pulse program
and decides what type of experiment has been performed. In case the nucleus is
unknown to the program, or the pulse program has a name that does not contain
a string “nq” nor “nQ” (with n=3, 5, 7, 9), the required information is asked for by
the program, in order to calculate the shearing correctly.
Note that using a user designed pulse program that contains e.g. a string “5q” but
performs a 3Q experiment (and vice versa) will yield erroneous shearing. When
started the AU program prompts for “Apply ABS2?” and “F1 shift in ppm:”. It is ad
-
visable to calculate a baseline correction after F2 Fourier transform. Note that the
range defined by ABSF1 and ABSF2 is used for this. You should make sure that
Table 17.4. Processing Parameters for 2D FT
Parameter Value Comments
F2 (acquisition dimension)
SI Usually set to one times zero filling.
WDW no Don’t use window function.
PH_mod pk Apply phase correction.
BC_mod no No DC correction is required after full phase cycle.
ABSF1 1000 ppm Should be outside the observed spectral width.
ABSF2 -1000 ppm Should be outside the observed spectral width.
STSR 0 Avoid strip FT.
STSI 0 Avoid strip FT.
TDoff 0 Avoid left shifts or right shifts before FT.
F1 (indirect dimension)
SI 256 Sufficient in most cases.
WDW no Don’t use window function, unless F1 FID is truncated.
PH_mod pk Apply phase correction.
BC_mod no No DC correction is required after full phase cycle.
ABSF1 1000 Should be outside the observed spectral width.
ABSF2 -1000 Should be outside the observed spectral width.
STSR 0 Avoid strip FT.
STSI 0 Avoid strip FT.
TDoff 0 Avoid left shifts or right shifts before FT.
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