208 (327) BRUKER BIOSPIN User Manual Version 002
Relaxation Measurements
The Saturation Recovery Experiment 16.2.4
For samples where cross-polarization is not possible, the inversion recovery ex-
periment would be very time consuming, as the recycle delay d1 would need to be
approximately 3x the longest T
1
value. For glycine at room temperature, this
would mean a delay of about 60s per scan, in addition to the variable relaxation
delay. The saturation-recovery experiment removes the need for long d1 by forc
-
ing the system into saturation at the beginning of each scan.
Sample: Glycine
Spinning speed: 10 kHz
Time: 20 minutes
Experiment setup
Start from standard carbon CP parameters, and set pulprog to satrect1.
Set zgoptns to –Ddec to turn on proton decoupling. If decoupling is not required
on a real sample, this can be left blank to turn off the decoupling.
Set p1 and pl1 to the measured carbon 90-degree pulse parameters (as used in
the CP T1 experiment, or see chapter Basic Setup Procedures). Set d1 to a rela
-
tively long value for the preparation experiments.
Set the number of pulses in the saturation train, l20, to zero, and acquire a spec-
trum. This will give an idea of the amount of signal, and thus how many scans
need to be acquired for each relaxation delay.
Create a new data set with iexpno, and set the saturation parameters, l20 = 5-
100 and d20 = 1-50 ms respectively.
Acquire a spectrum, and verify that saturation is complete – there should be no
signal at all.
Setting up the 2D experiment
Set the parameters for the 2D acquisition as detailed in Table 16.4..
For the variable recovery delay, the same values can be used as for the inversion
recovery experiment.
The recycle delay d1 can be very short, but take care not to exceed the duty cycle
limits: high-power pulsing should not exceed 5% of the total scan time. In the case
of decoupling, the acquisition time comprises most of the pulsing, so d1 should be
>20x aq – 1 second is reasonable in this case. If the experiment is run without de
-
coupling, then the saturation period is the only significant period of high-power
pulsing, and d1 can be shorter.
Acquire the 2D spectrum with zg.
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