MQMAS nutation NMR
applied to a crystal:
JDK1.1.8 applet

Home and Applets > MQ-MAS > JDK1.1.8 Java Applets for Single Crystal

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

Launch the MQMAS applet with Java Web Start.

MQMAS sequence with pulse lengths p1 and p2 for nutation NMR

The multi-quantum magic angle spinning (MQMAS) experiment on half-integer quadrupole spins was introduced by L. Frydman and co-workers. In the basic two-pulse sequence, it is an echo experiment involving transitions between non-consecutive energy levels during the excitation of the spin system by the first pulse. The MQ coherences generated by this pulse are converted back to -1Q coherence as an echo and an anti-echo by the second pulse. Mainly the central-transition signal is detected. The observation of the echo and anti-echo requires the optimization of the two pulse-lengths p1 and p2.

IMAGE: Parameters for the simulation of MQMAS echo and anti-echo amplitudes

The echo and the anti-echo amplitudes in this experiment are a product of two functions: the MQ excitation function A(p1) that depends on p1 and the conversion function B(p2) that depends on p2.

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 select either the echo signal or the anti-echo signal with the choice box.

Then, with the lower choice box we select one of the four types of calculation available:
(1) A(p1)B(): the echo amplitude with p1 variable and p2 constant;
(2) A()B(p2): the echo amplitude with p1 constant and p2 variable;
(3) B(p2): the conversion function;
(4) A(p1): the MQ excitation function.

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

Finally, we select the MQ coherence generated by the first pulse, shown in the text-area above the RUN button.

The following applet is initialized for the -3QMAS echo amplitude A(p1)B() of a spin I = 3/2 in a single crystal; the pulse length p2 is equal to 5 µs and p1 increases from 0 to 10 µs by 0.5 µs step. The experimental line intensities are identical to the simulated ones.

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

Solid-state NMR bibliography for:

Aluminum-27
Antimony-121/123
Arsenic-75
Barium-135/137
Beryllium-9
Bismuth-209
Boron-11
Bromine-79/81
Calcium-43
Cesium-133
Chlorine-35/37
Chromium-53
Cobalt-59
Copper-63/65
Deuterium-2
Gallium-69/71
Germanium-73
Gold-197
Hafnium-177/179
Indium-113/115
Iodine-127
Iridium-191/193
Krypton-83
Lanthanum-139
Lithium-7
Magnesium-25
Manganese-55
Mercury-201
Molybdenum-95/97
Neon-21
Nickel-61
Niobium-93
Nitrogen-14
Osmium-189
Oxygen-17
Palladium-105
Potassium-39/41
Rhenium-185/187
Rubidium-85/87
Ruthenium-99/101
Scandium-45
Sodium-23
Strontium-87
Sulfur-33
Tantalum-181
Titanium-47/49
Vanadium-51
Xenon-131
Zinc-67
Zirconium-91
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