NMR: Difference between revisions
From Pumping Station One
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* If the NMR has not been used in a long time, and you do not see a peak from your water sample, you may need to adjust the shunt mechanically. | * If the NMR has not been used in a long time, and you do not see a peak from your water sample, you may need to adjust the shunt mechanically. | ||
** You will need either a long brass flathead screwdriver or a long wooden tool to turn the screw deep inside the instrument (it should more very freely with almost no resistance). | ** You will need either a long brass flathead screwdriver or a long wooden tool to turn the screw deep inside the instrument (it should more very freely with almost no resistance). | ||
** | ** Hit Control-K to get out of GS if you are in there. Type W1 and enter a large value (like 40,000) for the Spectrum Width. What this does is effectively zooms out quite a bit as the peak is likely "off screen" when using more common values like 1,000 for spectrum width. Type SI and set the value to 4096. This will reduce the time it takes to obtain a spectrum, allowing for easier interactive adjustment to happen. | ||
** Once centered, you might want | ** Type GS and look for a peak. Turn the shunt counter-clockwise and you should see the peak move left. Clockwise to move right. With the water sample, you'll want it roughly in the center of the screen. | ||
** Once centered, you might want to have the electronic shimming routine do the rest of the fine tuning. Hit Control-K to get out of GS and type SHIM and hit enter. This will take a few minutes... | |||
== Operation / Background == | == Operation / Background == | ||
