Rotary-echo nutation NMR
applied to a crystal:
JDK1.1.8 applet
AIM: Determination of the quadrupole coupling from a featureless NMR lineshape
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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.
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 µs
MaxLength: the last variable pulse-length in µs
Step: the increment of the variable pulse-length in µs
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.
JDK1.1.8 applet for rotary-echo nutation sequence applied to a single crystal
Help for selecting all the simulated data of the line intensity text area in a JDK1.1.8 applet.