NMR pulse sequence:
shifted-echo MQ-MAS

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Shifted-echo MQ-MAS

Grandinetti and coworkers, who introduced the shifted-echo approach to DAS experiment, extended this approach to MQMAS.

Shifted-echo approach generates pure absorption 2D lineshape.

An additional selective pi pulse for the central transition is added at the end of the two-pulse sequence to shift the coherence transfer echo

The delay tau should be long enough so that the whole echo is acquired for t1 = 0. This delay is a multiple of the rotor period and about half the echo width.

PROCESSING: After the Fourier transform with respect to t2, a tau-dependent first-order phase correction is performed to remove the phase modulation due to the shift and a t1-dependent first-order phase correction to perform the shearing transformation. This results a 2D isotropic (in F1 dimension) anisotropic (in the F2 dimension) correlation spectrum.

Amplitude modulated shifted-echo 3QMAS sequence

The echo amplitude and the antiecho amplitude have opposite signs.

This figure represents the amplitude-modulated shifted-echo associated with 3Q-MAS experiment involving both pathways.

For a spin I = 3/2,

0Q -> +3Q -> +1Q -> -1Q is the anti-echo pathway,

0Q -> -3Q -> +1Q -> -1Q is the echo pathway.

For the other half-integer spins,

0Q -> +3Q -> +1Q -> -1Q is the echo pathway,

0Q -> -3Q -> +1Q -> -1Q is the anti-echo pathway.

ACQUISITION: Hyper-complex or TPPI


Phase modulated shifted-echo 3QMAS sequence involving the echo pathway

This figure represents the phase-modulated shifted-echo associated with 3QMAS experiment involving the echo pathway.

For a spin I = 3/2,

0Q -> -3Q -> +1Q -> -1Q is the echo pathway.

For the other half-integer spins,

0Q -> +3Q -> +1Q -> -1Q is the echo pathway.

ACQUISITION: F1-QF


Phase modulated shifted-echo MQMAS sequence involving the anti-echo pathway

This figure represents the phase-modulated shifted-echo associated with 3QMAS experiment involving the anti-echo pathway.

For a spin I = 3/2,

0Q -> +3Q -> +1Q -> -1Q is the anti-echo pathway.

For the other half-integer spins,

0Q -> -3Q -> +1Q -> -1Q is the anti-echo pathway.

ACQUISITION: F1-QF

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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