Dear colleagues,
Finally our 600MHz is in good condition. The line shape is stable. Please see the comparison in the attached spectra.
What the Bruker engineers did is to do cryoshimming again with the purpose to make the RT Z2 as small as possible, which is thought to play a critical role to produce the degraded peaks when the temperature is not stable. The plan works well. Currently Z2 is around -300, pretty small compared with its full range +/- 130'000. Before the cryoshimming Z2 was around 3000, though not very big but enough to cause problem. Our room temperature fluctuates up to 3.3 °C, which is really too harsh.
The 600 magnet is not stable totally at present with some drift of shim X. I don’t worry about this, because the drift value is getting smaller.
Thank you all for sharing your experience and ideas after my post.
Guangyu
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Received on Wed Mar 27 2019 - 22:45:45 MST