Table 1. Comparison of a Set of Commercially Available MAS Rotorsa.
| dout (mm) | din (mm) | sample volume (μL)b | max νR (kHz) | surface velocity (m·s–1) | RCF (106g) | Pcentri (bar) | frictional heating (K) | detection sensitivity (au) |
|---|---|---|---|---|---|---|---|---|
| Bruker Biospin | ||||||||
| 7.0 | 6.0 | 250 | 6 | 132 | 0.4 | 51 | n/a | 4.48 |
| 4.0 | 3.0 | 70.0 | 15 | 188 | 1.4 | 80 | 25 | 2.20 |
| 3.2 | 2.6 | 35.6 | 24 | 241 | 3.0 | 154 | 35 | 1.40 |
| 3.2 | 2.2 | 25.5 | 24 | 241 | 2.5 | 110 | 35 | 1.00 |
| 2.5 | 1.5 | 13.5 | 35 | 275 | 3.7 | 109 | 45 | 0.68 |
| 1.9 | 1.5 | 10.0 | 42 | 251 | 5.3 | 157 | n/a | 0.66 |
| 1.3 | 0.9 | 2.50 | 67 | 274 | 8.1 | 143 | 35 | 0.24 |
| 0.7 | 0.5 | 0.59 | 111 | 244 | 12.4 | 121 | 25 | 0.11 |
| Phoenix NMR | ||||||||
| 6.0 | 5.1 | 200 | 6 | 113 | 0.4 | 37 | n/a | 4.18 |
| 6.0 | 4.5 | 155 | 9 | 170 | 0.7 | 65 | n/a | 3.24 |
| 4.0 | 3.2 | 88 | 14 | 176 | 1.26 | 79 | n/a | 2.76 |
| 4.0 | 2.46 | 46 | 18 | 226 | 1.6 | 77 | n/a | 1.16 |
| 3.2 | 2.6 | 34 | 15 | 151 | 1.2 | 60 | n/a | 1.33 |
| 3.2 | 2.0 | 21 | 25 | 251 | 2.5 | 99 | n/a | 0.82 |
| 2.5 | 1.88 | 20 | 30 | 236 | 3.4 | 126 | n/a | 1.0 |
| 1.6 | 1.14 | 8 | 40 | 201 | 3.7 | 82 | n/a | 0.63 |
| 1.2 | 0.64 | 1.0 | 60 | 226 | 4.7 | 60 | n/a | 0.10 |
| JEOL Resonance | ||||||||
| 8.0 | n/a | 616 | 8 | 201 | n/a | n/a | n/a | 9.66 |
| 4.0 | n/a | 69 | 19 | 269 | n/a | n/a | n/a | 2.16 |
| 3.2 | 2.2 | 49 | 24 | 241 | 2.5 | 110 | n/a | 1.92 |
| 2.0 | 1.6 | 17 | 40 | 251 | 5.0 | 152 | n/a | 1.07 |
| 1.0 | 0.5 | 0.8 | 80 | 251 | 6.4 | 63 | n/a | 0.10 |
| Samoson’s lab (Darklands OU) | ||||||||
| 3.0 | n/a | n/a | 30 | 282 | n/a | n/a | n/a | n/a |
| 1.8 | n/a | 15 | 50 | 283 | n/a | n/a | n/a | 1.05 |
| 1.3 | n/a | 5.2 | 67 | 274 | n/a | n/a | n/a | 0.50 |
| 0.81 | 0.55 | 1.02 | 100 | 254 | 11.1 | 119 | 24 | 0.16 |
| 0.51 | 0.35 | 0.31 | 150 | 240 | 15.8 | 109 | 30 | 0.08 |
dout and din are the outer and inner diameters, respectively. Their maximum available MAS rates (νR) are given along with the velocity of the rotor surface. Maximal relative centrifugal forces (RCF = 1/g × 4π2νr2 × din/2) and pressures (Pcentri = 1/3ρ × 4π2νr2 × (din/2)2, where ρ is the sample density, estimated to be 1200 kg·m–3) are calculated at these speeds. Temperature increase induced by the rotation (frictional heating) is reported for the maximal MAS rate (see Figure 20 for Bruker systems). The detection sensitivity is the product of the rotor volume and the inverse of the outer diameter and is normalized with respect to a Bruker 3.2 mm standard wall rotor.
For rotors manufactured by Bruker, the entry corresponds to the active volume. For all other rotors, we report the actual sample volume.