1. Manuals
  2. Brands
  3. Tecnai Manuals
  4. Microscope
  5. T12
  6. Operating procedures manual

Tecnai T12 Operating Procedures Manual

Hide thumbs

Advertisement

Table of Contents

Tecnai T12 Operating Procedures
I.
II.
III.
V.
I. Initial Procedures
1.) Check that the "Vac." and "HT" buttons are lit on the microscope control panel
(check with the room lights on; the buttons automatically dim when the room is
dark). If "Vac." is not lit, contact the EM staff. If "HT" is not lit, press the button
to light it and proceed normally but make a note in the instrument log.
2.) Log in with the username and password created during training. If the vacuum
logger is running, close it and log off vacuumuser first.
3.) Sign in to the CharFac reservation system and the paper logbook.
4.) Launch the Tecnai User Interface and Digital Micrograph programs.
5.) Check that the microscope status reads
"COL. VALVES" and that the "Col. Valves
Closed" button is pressed (buttons appear
yellow when active).
6.) Fill the cold trap with LN2. The first Dewar
flask of the day should last ~30-40
minutes. Later dewars will each last 2-3
hours. Do not allow the cold finger to
warm or the vacuum will deteriorate
significantly.
Revised 03/25/2020
1
3
3
7
7
14
16
17
22
1

Advertisement

Table of Contents
loading

Related Manuals for Tecnai T12

Summary of Contents for Tecnai T12

  • Page 1: Table Of Contents

    3.) Sign in to the CharFac reservation system and the paper logbook. 4.) Launch the Tecnai User Interface and Digital Micrograph programs. 5.) Check that the microscope status reads “COL. VALVES” and that the “Col. Valves Closed”...
  • Page 2 7.) Open the “Vacuum Overview” screen by selecting it from the box in the bottom right corner of the screen. Check that IGP1 (Gun/Col) reads ~6 (log units). IGP1 indicates the vacuum level in the column and gun chamber. It should read 6 when the cold finger is chilled.

  • Page 3: Accelerating Voltage

    II. Accelerating Voltage 1.) If the “High Tension” button is lit and the displayed value reads 120 kV, proceed to Section III. 2.) The “High Tension" will be turned off (grey) for the first user each day. IGP1 must read < 10 before proceeding (see Section I).
  • Page 4 2.) Sample Holder Removal: a.) Reset the sample stage. b.) Always keep light pressure on the purple goniometer surface when removing the sample holder. Pull the holder straight back without rotating until it stops moving. c.) Rotate the holder clockwise until it stops. This rotation moves the guide pin (see steps 3 and 4) approximately from the 12 o’clock position to 5 o’clock.
  • Page 5 3.) Specimen Loading: Note: Never mount magnetic specimen discs in the clamp holder. The clamp spring is not strong enough to prevent the specimen from attaching to the objective lens polepiece. a.) Place the sample holder in the protective stand. b.) Remove the sample loading tool from the base of the stand.
  • Page 6 4.) Sample Holder Insertion: a.) Carefully line the pin on the sample holder with the 5 o’clock position on the goniometer and gently insert the holder until it stops. Be careful not to scrape the tip. You should feel some resistance as the holder o-ring seats in the airlock chamber.

  • Page 7: Emission Current

    f.) Gently allow the holder to slide into the microscope column until it stops. Tap the end of the holder to make sure it is securely seated. IV. Emission Current 1.) In the “Filament” window, set the “Heat To” value to the desired cathode temperature (consult the log sheet for recently used settings).
  • Page 8 1.) Finding the Beam a.) Click the “Col. Valves Closed” button to open the column valves (button turns grey and status becomes “Ready”) i.) If no beam is visible, try decreasing the magnification (RC “Magnification”) or moving the specimen stage (RC trackball), in case a grid bar is blocking the beam path.
  • Page 9 3.) Gun Shift a.) Select “Gun Shift” from the “Direct Alignments” panel. b.) Set the “Spot size” to 9. c.) Converge the beam to crossover using the “Intensity” (LC) knob and center the beam using the beam shift trackball (LC) Note: if the beam moves significantly when changing the intensity, roughly center the condenser aperture (see step 4.) before proceeding.
  • Page 10 5.) Condenser Astigmatism Note: Condenser lens astigmatism should be corrected when the beam does not expand in a symmetrical, circular fashion when the “Intensity” knob is adjusted. Astigmatism must be corrected separately for each spot size that is used. a.) Converge the beam to crossover (LC “Intensity”) and center it with the beam shift (LC trackball).
  • Page 11 7.) Beam Tilt Pivot Points a.) Focus (RC “Focus”) the specimen to minimum contrast. Note: the “Focus” knob has two parts. The smaller, Focus inner knob changes the focus. The larger, outer knob adjusts the “Focus step” i.e., how much the focus changes with each movement of the inner knob.
  • Page 12 of focus, but there should be little or no lateral movement. The amplitude of the image wobbler can be controlled by the focus step knob (outer ring of the RC “Focus”). c.) Press “Done” in “Direct Alignments”. Note: If the beam moves appreciably while the rotation center alignment is active, readjust the X and Y pivot points and beam shift (steps 7 and 8) and repeat.
  • Page 13 c.) Press the LC “Stigmator” button or click on “Objective” in the “Stigmator” window. d.) Use the MF knobs to adjust the objective stigmator. The goal is for the rings in the FFT to appear circular, not elliptical or hyperbolic. The rings will grow larger and astigmatism will be more apparent when closer to focus.

  • Page 14: Camera Control And Imaging

    VI. Camera Control and Imaging 1.) Camera Operation a.) The CCD camera is operated by the “CCD/TV Camera” panel, found in the “Camera” tab of the microscope interface. b.) Click “Insert” to extend the CCD camera into the microscope. c.) Lift the phosphor screen (LC button L1) so the beam can reach the camera. d.) There are three camera modes: •...
  • Page 15 Any files older than 1 week may be subject to deletion without warning if the drive(s) becomes full. a.) Save images to the “My documents” folder, preferably in a “T12” subdirectory. b.) At the end of your session, open WinSCP (shortcut on desktop) c.) Select the “data.charfac.umn.edu”...

  • Page 16: End Of Session

    c.) If artifacts persist, a new gain reference must be collected. To prepare a gain reference: i.) Move to an empty location, such as a large hole in the support film. This empty region must cover the entire CCD field of view. ii.) Spread the beam until it illuminates at least half of the viewing screen.

  • Page 17: Troubleshooting

    2.) If you are the last user of the day: a.) Remove the LN2 dewar, return the LN2 to the large dewar, and place the microscope dewar upside-down on its stand. Place a towel below the cold finger on the microscope to collect condensing moisture. b.) Run the cryo cycle, located in the flap-out panel from the “Vacuum”...
  • Page 18 d.) Check that the C2 lens (LC “Intensity”) is not severely under- or overfocused, spreading the beam to a point that it is too dim to see. The optimal C2 setting will vary with magnification but is typically 30–60%. e.) If no beam is still visible, try loading a previously saved gun alignment file. Alignments can be loaded through the “Alignments”...
  • Page 19 alignments are available, you have been switched to dark field mode; press the “dark field” button on the right panel to return to bright field. 3.) The objective or SA aperture cannot be found Do not randomly turn the knobs to look for it! This not only makes it even harder to eventually find, turning too far in either direction can also cause damage to the aperture mechanism (and has!) For the SA aperture, reduce the magnification, as it may be located outside the...
  • Page 20 7.) The MF knobs do not move the diffraction pattern Occasionally, the microscope will stop auto-assigning the multifunction knobs to diffraction shift when entering diffraction mode. Check the lower-left status box to verify that the MF knob assignments read “Diff shift”. If the MF knobs are assigned to a stigmator, this will override the diffraction shift.
  • Page 21 the MF knobs to their previous assignment. The image shift has three separate registers, like the stigmator controls, which can be used to store different position offsets. d.) Having the door open, talking, or large groups present in the instrument room will inevitably produce thermal and acoustic variations that will result in specimen drift.

  • Page 22: Addenda

    Myers”. You will receive a confirmation email from the server. Unsubscribe: email listserv@umn.edu with no subject. In the body type: “SIGNOFF <list name>” i.e., to remove yourself from the T12 list, send “SIGNOFF TEM-T12”. You will receive a confirmation email from the server. Revised 03/25/2020...

Table of Contents