(A PDF version of this page is available from the Handouts site)
This page contains pertinent information to help you when a problem arises. Please look through the list below to identify and find resolutions to the most common problems at our facility. If your problem is not listed, please contact the staff at 792 or leave a detailed voice message at 386 (Kermit) or 387 (Dan). In addition, please fill out our NMR incident report so that we may be better able to serve your needs. The incident report should be used even if you are able to fix the problem. Click here to get the NMR Incident report. For specral problems, see NMR Artifacts.
Broken Tube in the Magnet:
THIS MUST BE REPORTED AS SOON AS POSSIBLE TO MINIMIZE DAMAGE TO THE PROBE. DO NOT ATTEMPT TO REMOVE SAMPLE! PLEASE CONTACT NMR STAFF IMMEDIATELY (CALL 792, 386, OR 387). IF STAFF IS UNAVAILABLE, LEAVE MESSAGE AT 386 OR 387. ALWAYS LOG-OFF OF THE INSTRUMENT AND HANG A SIGN ON MONITOR STATING; 'BROKEN SAMPLE: DO NOT USE INSTRUMENT'.
Console is unresponsive to Commands (This is only for instruments running old software. For New software issues including VnmrJ not starting or VnmrJ starting but no icons, see below):
1. With the right mouse button, click once on the Solaris desktop background to reveal a menu. Click on Programs or Tools, then over to select Terminal… A Terminal window will pop-up.
2. In the Terminal window, type ‘su acqproc’ and hit Return. You will get a message indicating that acqproc is being ‘killed’. Also, in the ACQUISITION STATUS window in VNMR, STATUS should now read “inactive”.
3. Proceed to the NMR console, which is the big grayish box. See below for location of reset button for various instruments.
4. Push the reset button.
LOCATION OF RESET BUTTON FOR EACH INSTRUMENT Instrument (floor) Reset Button Location Mut: UnityPlus-500 (sb) In the big grayish box to the right of the computer (left for Mut). Open the left door and look for a large red button on the middle right. Maat & Imseti: UnityPlus-300 (1st) Open the left door of the console. Look for a large red button on the middle right.
5. Wait for at least 40 seconds.
6. In the terminal window type su acqproc and hit Return. This will take a few moments. Look at the ACQUISITION STATUS window in VNMR. Wait for STATUS to read “idle”.
7. In the VNMR command line (i.e. where you usually type e), type su and hit Return. The NMR should now be ready for use.
Console is unresponsive to Commands (This is only for instruments running NEW software. This includes Mut (500, B8), Anubis (500, B7), Ra (300, B8), Isis (600, B7), and the NMR's in room 125. For Old software, see above):
1. In the command line, type abortallacqs. The instrument status will go to Inactive. Wait for the status to return to Idle, then type fixshims. You will need to turn spinning back on and reestablish lock.
If the above fails, use the following procedure:
1. With the right mouse button, click once on the desktop background to reveal a menu. Click on Terminal… A Terminal window will pop-up.
2. In the Terminal window, type ‘su acqproc’ and hit Return. You will get a message indicating that acqproc is being ‘killed’. Also, in the ACQUISITION STATUS at the bottom of VnmrJ, STATUS should now read “inactive”.
3. Proceed to the NMR console, which is the big grayish box. Open the left door and look for the blue ethernet connector on the middle far left. Just above that connector is a small red button with the label 'reset' above it.
4. Push the reset button.
5. Wait for at least one minute.
6. In the terminal window type su acqproc and hit Return. Wait a few moments. Look at the ACQUISITION STATUS window in VNMR. Wait for STATUS to read “idle”.
7. In the VnmrJ command line (i.e. where you usually type e), type fixshims and hit Return. The NMR should now be ready for use.
VnmrJ program is unresponsive or does not open (This is only for instruments running NEW software. This includes Mut (500, B8), Anubis (500, B7), Ra (300, B8), Isis (600, B7), and the NMR's in room 125. For Old software, see above):
If after clicking the VnmrJ icon the program doesn't start within 30 seconds, please contact the NMR Facility to have your account activated on that machine. Please include your account name and the instrument you were trying to use (this includes the datastations as well).
If VnmrJ opens but does not display any icons or menu items or gives 'variable undefined' errors, please do the following:
- Exit VnmrJ.
- Right click on the Desktop and select Open Terminal.
- In the terminal window, type cd and hit <Enter>.
- Type cd vnmrsys and hit <Enter>.
- Type rm lock* and hit <Enter>.
- Restart VnmrJ.
Can't Lock on Sample: (PDF version)
This can be caused by several problems. Common reasons and their solutions are listed below:
Common Reasons for Inability to Lock Cause Result Solution No deuterated solvent No deuterium signal to lock on. Use a deuterated solvent like CDCl3. Shimming is very poor The signal is so broad that it is not well observed. Type fixshims to get a good start. Suspended particles This causes line broadening, which makes the signal intensity weaker. Filter your sample. Too concentrated There is little deuterated solvent to get a lock. Especially problematic when using CDCl3. Dilute your sample or use a solvent with more deuteriums (e.g. C6D6). Improperly gauged When injected, the sample is not in the coil. Eject sample and ensure that the sample resides between the white lines on the gauge. Lockpower is too low The sample is not receiving enough rf signal to flip the deuterium spins. Increase lockpower to 80% of max before trying to lock. Lockpower is too high (for multi-resonance samples) With solvents having more than one deuterium resonance (e.g. CD3OD, THF-d8), high lock power will cause all resonances to be excited. This makes locking on a single resonance difficult. Reduce the lockpower by 20 and find the lock signal. If you see the signal with 'bumps', reduce lockpower further. Lockgain is too low The signal from your sample is not amplified enough for you to see the signal. Increase Lockgain to maximum.
I Can't Access a Workspace (e.g. exp1, exp2) or, for New software, VnmrJ screen is mostly blank:
I Can't Eject my Sample:
Poor Shimming: (Click HERE to get a more detailed procedure for shimming. PDF format)
Common Reasons for Poor Shimming
|No deuterated solvent||No deuterium signal to lock on and, thus nothing to shim on.||Use a deuterated solvent like CDCl3.|
|Initial shimming is poor||Your peaks are very broad.||Type fixshims to get a good start.|
|Suspended particles||This causes line broadening, which makes the signal intensity weaker.||Filter your sample.|
|Too concentrated||Concentrated samples can be viscous, which will cause line broadening.||Dilute your sample.|
|Too little solvent||When injected, the sample is not properly positioned in the coil and the liquid/air interface is 'seen' by the coil. This will make shimming very difficult.||Add more solvent.|
|Improperly gauged||When injected, the sample is not properly positioned in the coil and the liquid/air interface is 'seen' by the coil. This will make shimming very difficult.||Eject sample and ensure that the sample resides between the white lines on the gauge.|
|Cheap, old, or stored in hot oven NMR tube||Poor quality NMR tubes are either very slightly out-of-round and/or have uneven wall thickness. This results in a flucuation in the field and thus poor line shape.||Throw away the NMR tube and get a tube that is, at the very least, rated for the field you are using. We recommend the Wilmad 528 series as a minimum.|
The Computer Screen is Blank:
The Temperature is too High/Low (OLD software):
The Temperature is too High/Low (NEW software):
The VNMR Screen Colors are Terrible (OLD software only):
The odd colors for your VNMR interface are usually a result of having too many windows/applications open. Since VNMR is generally the last to be opened, it is given the last dregs of color available, which turn out to be pretty awful. You should close all unnecessary applications prior to running VNMR.
My Sample is not Spinning (OLD Software):
My Sample is not Spinning (New Software):
My baseline rolls or is not flat (for 2D Spectra, see the Processing, phasing, and plotting 2D phase sensitive data Handout):
July 19, 2012
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