Rotary-echo nutation NMR
applied to a crystal:
JDK1.0.2 applet




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AIM: Determination of the quadrupole coupling from a featureless NMR lineshape

Rotary-echo sequence for nutation NMR

Despite the name of this sequence, we do not perform echo experiments because the signal is observed at the end of the second pulse. Two rotary-echo sequences are presented:

X-(-X): {+X,-X}-acq(y)

Even-X: {+X,-X}-acq(y)
        {-X,-X}-acq(y)

These sequences do not cancel spurious signals whereas the composite-pulse sequence does. On the other hand, if the two pulse-lengths are identical (p1 = p2), the X-(-X) sequence cancels signals with small and strong quadrupolar couplings.


IMAGE: Parameters for the simulation of rotary-echo nutation NMR line intensity

The left part of the panel indicates the parameters of the simulation. It is preset for a typical experiment on a spin I = 3/2. You can introduce your own values.

First, we select one of the two rotary-echo sequences with the upper choice box.

Then, we select one of the three types of line intensity calculation with the lower choice box:
(1) V-V: when p1 = p2 and varying simultaneously;
(2) V-F: when p1 is variable and p2 is constant;
(3) F-V: when p1 is constant and p2 is variable.

When p1 = p2, only the parameters for p1 are required.

When a pulse length is constant, it should be provided in the MinLength field.

MinLength: the first variable pulse-length in s

MaxLength: the last variable pulse-length in s

Step: the increment of the variable pulse-length in s

The following applet is initialized for the central-line intensity of a spin I = 3/2 in a single crystal excited by the X-(-X) rotary-echo sequence where the two pulse-lengths vary identically. The experimental line intensities are identical to the simulated ones.

 


JDK1.0.2 applet for rotary-echo nutation sequence applied to a single crystal Applet for calculating and fitting the NMR single crystal line intensity of quadrupolar spin excited by the rotary-echo sequence.
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