根据lock来匀场

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根据lock来匀场

1. 锁住氘信号:

A. 在vnmr 采样窗口中点击lock按纽.

B. 让lock处于off.状态

C.调整Z0到“正共振”状态.

D. 让lock处于auto或者on的状态.

E. 调整lock power，让 lock 信号可以观察到，但是不要使其饱和，如果饱和，信号将会大幅度的变化

F. 点shim 按纽. 改变匀场值到仪器的标准匀场值，标准样品的标准匀场值存在 StdShims中，参见Recalling and Saving Shim Values.

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If you are interactively optimizing Z1 and Z2 and their values are changing in a consistent direction as you switch from one shim to another, "overshim" Z1 by passing through the value that maximizes the lock and setting Z1 beyond this optimal value. Continue to optimize Z1 and Z2.

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2. Spin the sample at 20 Hz and adjust Z1 and Z2 interactively to produce the largest lock signal. If you change Z2 by a large value, readjust the field and phase of the lock.

3. Collect a spectrum (nt=1, ss=0, np=16448, rd=0, lb=0.3). If the spectral lines are narrow and symmetric with small spinning sidebands, the shims are OK.

4. If the spectral lines have a large hump, change Z2 until the lock level is degraded by 3-5%, optimize Z1, and collect a quick spectrum. If there is no improvement, change Z2 the other way, optimize Z1, and collect a quick spectrum. If there is still no improvement, see Shimming on the FID. When finished, reoptimize the lock.

Steps 5 through 8 are NOT recommended. WRITE DOWN THE ORIGIONAL SHIM VALUES OF ANY SHIM THAT YOU CHANGE AFTER THIS POINT, or store the shims in a file, before attempting these steps. See Recalling and Saving Shim Values.

5. If the spectral lines are wide at the base, optimize Z3, then optimize Z1 and Z2 interactively, and collect a quick spectrum. If the base is still wide, change Z3 enough to degrade the lock level by 5-10%, optimize Z1 and Z2, and collect a quick spectrum. If there is no improvement, change Z3 the other way, optimize Z1 and Z2 interactively, and collect a quick spectrum. If there is still no improvement, see Shiming on the FID.

6. If the spectral line has a hump near the base, optimize Z4, then optimize Z1 and Z2 interactively, and collect a quick spectrum. If the base still has a hump, change Z4 until the lock level is degraded by 5-10%, optimize Z1 and Z2, and collect a quick spectrum. If there is no improvement, change Z4 the other way, optimize Z1 and Z2 interactively, and collect a quick spectrum. If there is still no improvement, see Shimming on the FID. If there is an imporvement, optimize Z3, then Z1 and Z2 interactively, then reoptimize the lock.

7. If spinning sidebands are >3% of line height, record the lock level, then turn off the spinner. If the lock decreases more than 10%, adjust X and ZX interactively for the tallest lock signal, then adjust Y and ZY interactively for the tallest lock signal, turn spinner on, then collect a quick spectrum. If the lock doesn't drop upon turning off the spinner, start again at step 1.

8. If there are two sets of spinning sidebands on each side of the peak, record the lock level, then turn off the spinner. If the lock decreases more than 10%, then adjust XY and X²-Y² for the tallest lock signal, turn spinner on, then collect a quick spectrum. If the lock doesn't drop upon turning off the spinner, start again at step 1.

Recalling and Saving Shim Values

1. Optimized shims for teh standard sample are taped to the table in front of the spectrometer.

2. To recall shim values during the same shimming session, click on first to recall the origional shims, click on best to recall the best set of shims during the session. Once you exit the shimming window, this method is lost.

3. To recall the standard shims, type rts('StdShims'). These shims are also listed at the console.

4. To save your shim values, type svs('filename') . To retrieve your shim values, type rts('filename') . Shims are stored in /home/Research/vnmrsys/shims. Shim files older than one month should not be used. Shim files are frequently deleted and are not archived.

[此贴子已经被作者于2006-11-17 19:00:47编辑过]

tlmowen10

sf

顶一下！！

ylliny

xiexie