• Record a conventional 1H spectrum

From the reference ¹H spectrum create a new dataset with edc and change the pulse program to pulprog cpmg. All other parameters as in the ¹H spectrum. This experiment is a simple echo experiment recorded as a 2D data set (change parmod to 2D in eda) in which the interpulse delays are varied over the course of the experiment. A 1D spectrum is obtained for each value, and the results are stored in a 2D data set.

This experiments is better performed without sample spinning.

Other parameters to consider:
It is very important to use a long recycle delay, usually d1=5*T₁(¹H).
td1 (=10) is the number of experiments (or number of entries in vc-list).
o1 is set on resonance to the selected signal.
d20 is the fixed echo time to allow elimination of diffusion and J-mod. effects (d20=10m). Define a vc-list by typing edlist vc t2delay. Enter the number of repeated cycles (c) as, for instance:

2
20
50
100
200
300
400
500
750
1000

and include it in the acquisition parameters by typing vclist t2delay. The total evolution time is (d20*2+p2)*c.

(minimum number of scans ns=8 and ds=16).

The spectra can be processed by the automation program proc_t1 or manually entering xf2. A linebroadening is usually applied (lb(F2)=2Hz). In all cases, set SI1 as a power of two greater than or equal to the number of counters in the vclist (SI1=16). More details in T₁ calculation.

It is advisable to store all acquisition and processing parameters (for instance, with the command wpar cpmg all) to be used later.