Hahn echo nutation NMR
applied to a crystal:
JDK1.1.8 applet




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

Hahn echo sequence with pulse lengths p1 and p2 for nutation NMR

In the basic two-pulse Hahn echo sequence on half-integer quadrupole spins, the single-quantum coherences generated by the first pulse are refocused as echoes by the second pulse. The observation of these echoes, located at tau2 = tau1, requires the optimization of the two pulse-lengths p1 and p2.

An echo amplitude is a product of two functions. The first function A(p1), called the excitation function, depends on p1. The second function B(p2), called the conversion function, depends on p2.


IMAGE: Parameters for the simulation of Hahn echo amplitude in nutation NMR

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

First, we should select with the choice box one of the three types of calculation available:
(1) A(p1)B(): the echo amplitude when p1 is variable and p2 is constant;
(2) A()B(p2): the echo amplitude when p1 is constant and p2 is variable;
(3) B(p2): the conversion function.
The first two cases could be checked experimentally, whereas the last case is a theoretical result.

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

Then, we select the observed coherence, shown in the text-area above the RUN button.

The following applet is initialized for the conversion function of the central-transition Hahn echo amplitude B(p2) of a spin I = 3/2 in a single crystal. The experimental line intensities are identical to the simulated ones.

 

JDK1.1.8 applet for Hahn echo nutation NMR applied to a crystal Applet for calculating and fitting the single crystal NMR line intensity of quadrupole spin excited by the two-pulse Hahn echo sequence.

Help for selecting all the simulated data of the line intensity text area in a JDK1.1.8 applet.

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