Bruker BioSpin Solid State NMR, User Manual

Page: 162 / 328

162 (327) BRUKER BIOSPIN User Manual Version 002
REDOR
preparation will fail (compare
Figure 12.5.
). By clicking OK, topspin will automati-
cally pick all the intensities for your measured REDOR experiments. These values
are then saved in the processed data directory (
\data\user\nmr\experi-
ment\exp#\pdata\1 ) in the file “ t1t2.dx ”. The intensities are saved in two columns
for each peak, while the first column represents a arbitrary x-scale, the measured
intensities are within the second column. Remember, because of the used pulse
program “cpredori” every odd line contains an intensity value for an REDOR spec-
trum (S’) and every even line the corresponding intensity of the ECHO experiment
(S
0
).
Figure 12.5. Setting the Correct Analysis Parameter
After importing this file into Excel or any other program (using either “Origin” or
“Igor” is recommended) for calculating the values for (S
0
-S’)/S
0
, these normalized
intensities are plotted versus the evolution time of each spectrum (which is a mul-
tiple of “T
R
*2”) as it is shown in
Figure 12.6.
. The x-axis is therefore calculated by
(Eq. 12.2)
where i is the number of the corresponding data point (S
0
-S’)/S
0
(the number of
the S
0
/S’ set within the 2D data set). In this experiment MAS spinning speed was
10 kHz resulting in data points every 200ms. Note, only the analysis of the low
field shifted peak is shown here, corresponding to the alpha-glycine modification
of the measured sample.
) 2 2 ( ) MASrate 1 (
− ⋅
i