Autoshimming Interactive autoshimming should not be used as a replacement for manual shimming. Autoshimming is fast and efficient only when the shims are near optimum. Autoshimming only on Z1 and Z2 is recommended. Do not autoshim on shims other than Z1, Z2, and Z3. 1. In the vnmr acquisition shim window, click on auto. 2. Select m>m to "start with medium and end with medium" shimming quality. 3. Select the set of shims to be used by the autoshimming routine. 4. Click on start. The start button will change to stop. The autoshim is finished when the stop button changes to start. Use background autoshimming for long data acquisitions EXCEPT for 15N and spin-lock experiments: 1. While setting up your experiment parameters, type method('z1z2') for samples > 0.5 ml, type method('z1z2z3') for samples £ 0.5 ml. 2. After the experiment has started, type shim.
Table 1 lists the room temperature shims. If you change a shim, you should reoptimize the other shims which interacts with the changed shim. Shims which start with 'Z' (the spinning shims) should be optimized with the spinner ON, while shims that start with 'X' or 'Y' (the non-spinning shims) should be optimized with the spinner OFF.
Shims (ethylbenzene in chloroform): Linewidth = ______ sidebands = _____ | Shim | Interacts With | Value | Shim | Interacts With | Value | Lock | none |
| X1 | none |
| Z1C | none |
| Y1 | none |
| Z2C | Z1 |
| XZ | X1 |
| Z1 | none |
| YZ | Y1 |
| Z2 | Z1 |
| XY | X1,Y1 |
| Z3 | Z1,Z2 |
| X2Y2 | X1,Y1 |
| Z4 | Z1,Z2 |
| X3 | X1,Y1 |
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| Y3 | X1,Y1 |
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