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Electron Microscopy Facility
Subsidiary of the Research and Graduate Studies Office of the AVP

Tecnai F20 TEM Sample Loading

By Paul Minson,
May 05, 2023 02:24 PM

Tecnai F20 

The following procedures are meant to assist the new user to start a “normal use” microscope session. If there are questions with any of the steps, or if it appears there may be a problem with the microscope, DO NOT TRY TO SOLVE IT YOURSELF—GET HELP.

CHECKLIST Starting microscope operation

The checklist is meant as a reminder. If you need more than a reminder, read the sections referred to by the corresponding steps. FEEL FREE TO ASK FOR HELP! The lab manager is here to assist and train users as well as keep the instrument in working condition, so he is willing to help. You can also get more details to some of the information below by opening the help files (F1) from the Tecnai user interface software.

  1. Check the lighted buttons on the right side of the column. The lights should be lit from left to right: RED-WHITE-WHITE. If it is otherwise, see the Lab manager.
  2. Fill the cold trap with liquid nitrogen.
  3. Wake up the computer by moving the mouse, if the screen is blank.
  4. Check the Vacuum control panel. The gun vacuum should be at 1 (log units), and the column vacuum should be around 6 to 7 (log units). The camera should be around 20-30 (log units). Check that the column valves are CLOSED.

  5. If necessary, remove the specimen holder that is currently in the microscope by following the steps below. 

    1. Ensure that the column valves are closed. In the Vacuum control panel the “Col Valves Closed” button should be YELLOW. 
    2. Go to the Search work set, and on the Stage control panel flap-out menu under the “control” tab press the “Reset the holder” button. Wait for the tilts to go to zero.
    3. Stand up.
    4. Unplug the beta-tilt cable (if using the double-tilt holder).
    5. While pressing on the purple plate, pull the specimen rod straight out until it stops (continue holding the rod or it will go back into the column).
    6. Turn the specimen rod clockwise (do not continue pulling-JUST TURN) until it stops. Before performing the next step make sure the rod stays turned completely clockwise.
    7. Place your left hand on the base of the specimen exchange area to press the purple plate, and your right hand on the rod. Place your right thumb on your left hand and use your thumb to break the vacuum of the specimen exchange chamber. 
    8. After breaking the vacuum, gently and steadily pull the rod completely out of the specimen exchange.
  6. Insert a specimen into a specimen holder.

  7. Insert the holder into the microscope by following the steps below.

    1. Check that the column valves are CLOSED.
    2. Stand up.
    3. Before insertion, align the small pin near the end of the specimen rod with the 3 o’clock position on the front of the specimen exchange chamber. Slide the rod into the exchange chamber until it comes to a stop. Applying gentle pressure, rotate the holder clockwise until the pin hits the mark “Close” at 5 o’clock on the front of the specimen exchange chamber, at which point you will feel it slide further in.
    4. Slide the specimen rod further into the specimen exchange until it comes to a stop (about 0.25” further). If you are at the right stop, the rod will not twist clockwise anymore. It will be “snug” to the touch. (It will be exactly 2 and 3/8 inches from the front of the specimen exchange.) The little red LED on the front of the specimen exchange will light up at this point.
    5. CAREFULLY plug in the beta-tilt cable if using the double-tilt holder.
    6. Select the specimen holder in the Tecnai User Interface (bottom middle) and select ‘return’.
    7. Select ‘return’ again for the dialogue “Connect B tilt cable.”
    8. NOW WAIT FOR THE PUMP TIMER COUNTDOWN AND RED LED TO GO OFF BEFORE PROCEEDING.
    9. Once the red LED has gone off turn the rod counter-clockwise SLOWLY, 120 degrees, so that the pin has moved to the 12 o’clock position labeled “open”. After 120 degree turn the rod will feel that it is being pulled into the column.
    10. Allow the rod to go into the column completely. 
    11. Shut off the turbo pump by deselecting the “Turbo on” button on the Vacuum control panel.
  8. Wait for the column vacuum to drop below 10 (log units), then open the column valves. The beam should now be visible. (If you cannot find the beam, get help from the lab supervisor.)

CHECKLIST  Ending a microscope session

When you are finished working with the microscope follow the steps below:

  1. Turn the magnification to a reasonable level (around 8000x).
  2. Expand the beam to fill the phosphor viewing screen.
  3. Close the column valves. 
  4. Go to the Search workset, and on the Stage control panel flap-out menu press the “Reset the holder” button under the “control” tab. Wait for the tilts to go to zero.

  5. Remove the specimen holder. 

    1. Ensure that the column valves are closed. In the Vacuum control panel, the “Col Valves Closed” button should be YELLOW. 
    2. Stand up.
    3. Unplug the beta-tilt cable (if using the double-tilt holder).
    4. While pressing on the purple plate, pull the specimen rod straight out until it stops (continue holding the rod or it will go back into the column).
    5. Turn the specimen rod clockwise (do not continue pulling-JUST TURN) until it stops. Before performing the next step make sure the rod stays turned completely clockwise.
    6. While pressing on the purple plate, pull the specimen rod straight out to break the vacuum of the specimen exchange chamber. 
    7. After breaking the vacuum, gently and steadily pull the rod completely out of the specimen exchange.
  1. Remove the specimen from the specimen holder.