Rotating powder line intensity simulation including NMR probehead deadtime

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Line intensity simulation including NMR probehead deadtime

AIM: We provide a SIMPSON1.1.1 Tcl script for simulating the effect of NMR probehead deadtime on the central-line intensities in one-pulse MAS NMR applied to half-integer quadrupole spin in a powder.

Method: Instead of using the delay command to simulate the deadtime, we use the pulse command. We analyze the results obtained in decreasing the RF amplitude from 1 Hz to 0 Hz, via 0.001 Hz and 0.000001 Hz.

(A) SIMPSON1.1.1 Tcl: onepowderMAS-deadtime.in

The parameters for these simulations are:

The corresponding SIMPSON1.1.1 Tcl script for fitting the weak RF pulse amplitude and that for fitting the weak RF pulse amplitude and the quadrupole coupling constant are also available.

(B) Result

The simulated central-line intensities versus the strong RF pulse duration t for the four weak RF pulse amplitudes are gathered in the following table.


t
(μs)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

1-Hz
RF amplitude
0
0.182193018
0.0979927806
-0.088359578
-0.0983289152
0.0594444674
0.127937818
0.0247682716
-0.0817982774
-0.0462399493
0.0723006936
0.0775342799
-0.0104305579
-0.0509575505
0.00469790108
0.0556601961
0.0346636019
-0.0223360065
-0.0209033572
0.023717633
0.0419457937

0.001-Hz
RF amplitude
0
0.182191968
0.0979958634
-0.0883554318
-0.0983317506
0.0594375688
0.127938414
0.0247765951
-0.0817951103
-0.0462480946
0.07229373
0.0775403402
-0.0104213664
-0.0509591817
0.00468879641
0.0556574129
0.034671224
-0.0223292586
-0.020907561
0.0237097787
0.0419453603

0.000001-Hz
RF amplitude
0
0.182191967
0.0979958665
-0.0883554277
-0.0983317535
0.0594375619
0.127938414
0.0247766034
-0.0817951071
-0.0462481027
0.072293723
0.0775403462
-0.0104213572
-0.0509591834
0.0046887873
0.0556574101
0.0346712316
-0.0223292518
-0.0209075652
0.0237097708
0.0419453599

0-Hz
RF amplitude
0
0.182423558
0.0989424049
-0.0905746502
-0.0995905549
0.0637974991
0.129704616
0.0234087454
-0.0800400754
-0.0394933071
0.0702655428
0.0709753475
-0.0126538606
-0.0487570241
0.00684655207
0.0564105692
0.0369406466
-0.0167652653
-0.018874834
0.0129901036
0.034967544

(C) Conclusion

When the weak RF amplitude tends to zero, the central-line intensities do not tend to those of the weak RF pulse with zero amplitude. Therefore, the pulse command in SIMPSON1.1.1 should be used with a non-zero RF amplitude. Obviously, this is its main function.

The problem is that replacing the pulse command with zero RF amplitude in the Tcl script by the delay command generates the same central-line intensities. We expect that the delay command provides us with central-line intensities similar to those generated by the pulse command with 0.000001-Hz RF amplitude.

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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