2.4 Spinning the Sample
01-999162-00 C0402 VNMR 6.1C User Guide: Solid-State NMR
26
9. Install the probe into the magnet.
10. Set the bearing pressure to a value appropriate for the rotor speed you will be using,
see Table 3 and Table 4 for 7 mm and 5 mm rotor bearing pressures.
11. Open the drive value completely.
The rotor may initially spin when using older controllers but will stop when the
electro-pneumatic valve engages.
Regulating Spinning Speed
Direct input of the spinner speed (using the slider bars in the Spinner Control Window, see
Figure 3) uses the closed-loop mode of the spinner speed regulation option. The speed can
be increased or decreased by any value and the speed is safely ramped to the new value.
Making small changes in speed (1000 to 2000 Hz) is good practice, until you are
comfortable with the operation and reliability of a particular rotor and endcap combination.
Never exceed the rated speed for any of the rotor parts or probe.
1. Set the slider bar to 2500.
The spinner should regulate to ±2 Hz or better within about 30 seconds to 1 minute.
2. Experiment with a number of set points within the rated speeds of the sample rotor
and probe.
3. Set the desired spin speed using the slider bar.
Regulating Spinning Speed within VNMR
This procedure describes how to regulate spinning speed by entering commands in the
VNMR input window.
1. Start the rotor speed controller as described in the procedure “Starting the Spinner
Speed Controller” on page 25.
2. Click on the button next to Allow spin control in an experiment with go.
This button disables the speed in the Spinner Control window and transfers spin rate
control to the spin parameter in VNMR.
3. Set up a typical solids experiment:
a. Set spin to the desired speed.
b. Enter in=’ny’ go.
The spinner regulates at the value of spin. Include a pre-acquisition delay pad to
give the spinner time to stabilize. The parameter spin can be included in an array
to obtain multiple spin rates in a single experiment. In an array of spin, the
pre-acquisition delay is applied before each FID.
4. Click next to Allow spin control in an experiment with go to return control to the
Spinner Control window after the experiment is complete.
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