University of California, Riverside

NMR Facility

Bruker EMX EPR Help Sheets

bruer emx epr

Bruker EMX basic operation

EMX ZoomedSystem Startup

  1. Sign in in the log book.
  2. Make sure the chilled water is on.
  3. Turn on the heat exchanger.
  4. Turn on the power supply (Do Not Turn On The Magnet!)
  5. Turn on the EMX console.
  6. If you want to use the Gauss Meter start it up by double clicking the bootp desktop icon. Wait for a response indicating the bootp process has completed. Stow the bootp window.
  7. Start the Win-EPR Acquisition software. The icon is on the desktop.
  8. Turn on the magnet.

Cavity Tuning

  1. Click on the MW icon. The Microwave Bridge Control window will pop up.
    Microwave Bridge Control Window
  2. The bridge will be in the standby mode. Select Tune and set the microwave attenuation to 25 dB.
  3. Wait a few seconds to allow the frequency to set. Adjust the frequency to locate the cavity dip and set it so that the frequency marker is at the bottom of the dip. This should be the point where the dip is the deepest.
    Microwave Bridge Control Tuning
  4. Select operate. Set the microwave attenuation to 40 dB. The AFC meter AFC meter should be in the green at this point. If not adjust the frequency until it is. If the frequency is close you can use the fine tune button.
  5. Adjust the diode bias so that the meter is centered in the green. Diode meter
  6. Lower the microwave attenuation by 10 dB. If the diode current meter deflects all the way to one side or the other increase the attenuation in 1 dB increments until the meter is on scale.
  7. Adjust the iris up or down so that the diode current meter is centered. Make sure the AFC stays in the green throughout the process. If not adjust the frequency to bring it back.
  8. Repeat steps 5 and 6 until you have reached 10 dB and the diode meter is centered.
  9. Adjust the phase so as to maximize the diode current. Use the iris to bring the diode current back to the center.
  10. Set the microwave attenuation back to 40 dB. Make sure the AFC is still in the green. If the diode current has moved off center repeat steps 5 - 10.

Recording a Spectrum

  1. Click the I-icon(Interactive) icon. The Interactive window will pop up.
    Interactive Spectrometer Control Window
  2. If you have changed cavities make sure to change the calibration file. You can do this by clicking Signal Channel Tuning Options then select change file.
    Signal Channel Options window
  3. Set the desired center field, sweep width, modulation amplitude, modulation frequency, receiver gain, time constant, conversion time and microwave attenuation.
  4. Open a spectrum window by clicking the new spec button icon.
  5. In the interactive window click on set parameters to spectrum. The mouse cursor will change to a P. Move the cursor into the new spectrum window and click. The parameters will be transferred and the cursor will change back to an arrow.
  6. Alternatively you can open an existing file which will load its parameters. Then drag the spectrum into a new spectrum window. This is the recommended procedure as any changes made to the parameters in the opened file will be over written if a save is executed.
  7. Click the run button icon and the sweep will begin. Adjust your parameters if necessary and rescan. Parameters can be adjusted in the interactive window or in the parameters window associated with the highlighted spectrum window. Use of the parameters window is necessary if you want to do more advanced scans.
    standard parameter window
  8. Once you are satisfied with your spectrum you can save it to disk by selecting save as under the File pull down menu.

System Shutdown

  1. Put the microwave bridge in standby mode.
  2. Turn of the magnet.
  3. Close Win-EPR Acquisition.
  4. Close the bootp window.
  5. Turn off the EMX console.
  6. Turn off the power supply.
  7. Turn off the heat exchanger.
  8. Sign out in the log book.


You must be checked out on the instrument before you can schedule time. To get checked out please contact Dan Borchardt Chemical Sciences 120 2-3628, Once you have been checked out you may request a schedule user ID and password.

More Information

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University of California, Riverside
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Riverside, CA 92521
Tel: (951) 827-1012

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