NMR Program - RF Program

Purpose

This is another solid state MAS probe from 31 mm bore family designed to fit inside our high field 830 MHz magnet (29 mm space). The probe is equipped with custom miniature stator (ICBP, Estonia), which utilizes standard 4 mm zirconia rotors from Bruker. Sustained spinning speed are up to 10 kHz. The RF channel can be tuned to most low-gamma nuclei (30...145 MHz) by choosing appropriate frequency insert and attaching it to the probehead.

Applications

The primary use of this probe is for solid state NMR applications in a variety of solid materials such as glasses, zeolites, or semiconductors, that contain low gamma nuclei such as 99Ru, 109Ag, 49Ti, 25Mg, 67Zn, 33S, and other. High magnetic fields not only provide much needed sensitivity but higher Larmor frequencies also reduce the probe ring-down time.

25Mg MAS (@ 10 kHz) spectrum of PMN at 19.6 T
(Gina Hoatson, College of Williams and Mary)

Tuning Table

Use this table to select frequency insert for your nucleus. If isotope is not in the table, but its resonance frequency falls within 30...139 MHz range, contact Peter Gor'kov to arrange new insert. Q values are loaded values for probe with no sample⁺. Tuning range for each insert, F min...F max, is defined as frequency range where RF reflection is less than -35dB.

Insert (pF)	F min (MHz)	F max (MHz)	Isotopes	Q (@ -3dB)
85	37.7	39.5	105Pd, 99Ru, 109Ag, 39K, 163Dy	71
54	45.2	48.3	143Nd, 49Ti, 47Ti, 53Cr	72
45	48.3	52.3	25Mg, 67Zn	75-77
37	52.2	57.3	95Mo, 201Hg, 97Mo, 43Ca	77-81
28	57.8	65.2	14N, 33S, 189Os	84-87
None	98.8	139	175Lu, 181Ta, 123Sb, 133Cs, 17O, 9Be, 139La, 6Li, 2H, 209Bi	110-126

⁺Unloaded Q value of the coil is approximately twice that.

Pressure Guide

Table below shows values of bearing and drive pressures for MAS stator. The values are approximate and may vary with packing accuracy.

Bearing pressure (Bars)	Drive pressure (Bars)	Spinning speed (Hz)
3.0	0.5	3900
3.0	1.0	6200
3.0	1.5	7800
3.0	2.0	9300
3.0	2.5	10500
3.0	3.0	11600⁺
3.5	3.5	12600⁺
3.5	4.0	13400⁺
3.5	4.5	14000⁺

⁺Note: while this stator can reach higher speeds, it was designed for spinning at 10000 Hz and less. Overspinning is risky and increases possibility of rotor crash.

Publications
...using this intrument

1. G. Wu et al., J. Am. Chem. Soc. 125 7182-7183 (2003), PDF
2. A. Wong et al., Phys. Chem. A 108 (47), 10551 (2004), PDF
3. J.B.D. Lacaillerie et al., J. Phys. Chem. B, 109, 14033 (2005), PDF
4. J.B.D. Lacaillerie et al., Cement Concrete Res, 36 (9), 1781 (2006), PDF
5. P. Duxson et al., Ind. Eng. Chem. Res. 45, 9208-9210 (2006), PDF
6. S. Prasad et al., J. Non-Crystalline Solids, 352 (26-27), 2834 (2006), PDF
7. A. Wong et al., J. Phys. Chem. A, 110 (33), 10084 (2006), PDF