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Revised 03/25/2020 

 

Tecnai T12 Operating Procedures 

I. 

Initial Procedures 

1

 

II. 

Accelerating Voltage 

3

 

III.  Specimen Loading and Holder Insertion/Removal 

3

 

IV.  Emission Current 

7

 

V. 

Alignment 

7

 

VI.  Camera Control and Imaging 

14

 

VII.  End of Session 

16

 

VIII.  Troubleshooting 

17

 

IX.  Addenda 

22

 

 

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. 

Содержание T12

Страница 1: ...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...

Страница 2: ...en by selecting it from the box in the bottom right corner of the screen Check that IGP1 Gun Col reads 6 log units P3 indicates the camera vacuum level It should read 35 P1 indicates the pressure in the buffer tank and P2 the pressure in the backing pump line This dialogue box is used to select the vacuum overview or any of several other information or setup tabs ...

Страница 3: ... Continue in 20 kV increments waiting 1 2 min at each If the emission current remains high 1 2 µA return to the previous step for several minutes Note The HT may switch off and become disabled when reaching 40 kV If this occurs simply press the main HT console button to re enable it see Section I click the High Tension again at 40 kV and continue III Specimen Loading and Holder Insertion Removal N...

Страница 4: ...il it stops This rotation moves the guide pin see steps 3 and 4 approximately from the 12 o clock position to 5 o clock d Gently while keeping pressure on the goniometer pull the sample holder back to break the airlock vacuum This will require a small amount of force e Remove the holder straight back out of the column while being careful not to scrape it along the inside of the airlock f Be carefu...

Страница 5: ... and gently raise the clamp straight up until it stops d Place the specimen grid into the recess at the end of the holder e Gently lower the clamp straight down to hold the grid securely Return the tool to the base of the holder stand f Retract the holder slightly and turn it upside down Tap the back end several times then turn the holder upright and check that the grid has not moved movement sugg...

Страница 6: ...mpu stage will go on Do not move the holder while the red stage LED is lit c The pumping time remaining will be visible in the Vacuum Overview window d Select the specimen holder type Single Tilt from the box in the interface Be sure to click the button to confirm the selection e When the pump times ends status reads COL VALVES and the red stage LED goes out support the purple goniometer surface w...

Страница 7: ...n Step setting controls the bias voltage on the Wehnelt cylinder A higher step value decreases the bias This produces more emission current but increases the energy spread and source size of the beam V Alignment Note Align the microscope from the top gun down Press F1 at any time for online help with an alignment Begin with the objective and SA apertures removed Leave a condenser aperture inserted...

Страница 8: ...agnification RC Magnification in the 10 60 kx range and set Spot size to 3 b Center the beam using the beam shift LC trackball and spread the beam LC Intensity clockwise from crossover to 3 4 the size of the screen Note If the beam is very asymmetrical roughly adjust the condenser stigmation see step 5 c Select Gun Tilt from the Direct Alignments panel in the Tune workspace d Adjust the gun tilt u...

Страница 9: ...sizes 3 and 9 g Press Done in Direct Alignments h If the gun shift must be adjusted a substantial amount and it results in a significant change in the measured exposure time at a given spot size re check the gun tilt alignment 4 Centering the Condenser Aperture a Select the desired condenser aperture 4 is largest 1 is smallest using the large outer knob on the aperture b Converge the beam to cross...

Страница 10: ... Adjustment Note all alignments beyond this point depend on the objective focus To ensure proper alignment both the specimen and objective lens focus must lie on the eucentric plane of the microscope This step will position the specimen a Find a point of interest on the specimen using the stage trackball RC b Activate the Alpha wobbler LC button L2 by default The stage will begin rocking through a...

Страница 11: ...ents f Repeat steps b e for Beam tilt pp Y 8 Beam Shift a Converge the beam to crossover LC Intensity and center it using the LC trackball b Select Beam shift from Direct Alignments and use the MF knobs to re center the beam on the screen c Press Done in Direct Alignments 9 Rotation Centering Note Rotation centering is the most important alignment for high resolution work on this microscope It sho...

Страница 12: ...central diffraction spot using the MF knobs b Select and insert the desired objective aperture see aperture figure in step 4 The aperture should be visible in the diffraction plane c Center the aperture around the central spot aperture X and Y knobs d Deselect Diffraction to return to imaging mode Note If the aperture is not visible in the diffraction pattern do not randomly adjust the aperture as...

Страница 13: ... tune the stigmator settings e Click None in the Stigmator window or press the LC Stigmator button Note Objective astigmatism should be checked periodically throughout a session It can be changed by changes in magnification mode spot size Z height of the sample or objective aperture size or position Note Each stigmator has three registers available Clicking on a register selects among them These c...

Страница 14: ...the beam can reach the camera d There are three camera modes Search is a high refresh rate lower resolution mode used for viewing and focusing on the specimen in real time Preview is a slower higher resolution mode that uses half the CCD area to preview the final acquired image quality Acquire is used to a capture a single image from the whole CCD detector Note The parameters for any of these sett...

Страница 15: ...u start typing your username it should jump to it You can drag files from the T12 PC to the right hand window to transfer them to your storage directory If you use multiple instruments you may want to make a T12 directory here e After transfer close WinSCP and shutdown normally f See addendum for instructions on remote file access 3 Dark and Gain References If consistent artifacts are present in a...

Страница 16: ...ndenser aperture inserted in out out b Leave the column valves closed c Place the viewing screen down cover the window with the rubber mat d Switch the filament off Filament button in the Filament panel e Leave the magnification in the SA range preferably 2400 This is essential to maintain stable objective lens current and prevent thermal drift for the next user f Remove the sample holder be sure ...

Страница 17: ...um monitor username vacuumuser password vacuum c The Vacuum Logger software should start automatically Click Log Start to begin logging the vacuum levels Create a new file using today s date mm dd yyyy as the file name include zeros in the day month VIII Troubleshooting 1 No beam is visible There are several possible causes for no beam being visible Try the following steps until a beam can be foun...

Страница 18: ...button then click apply If desired alignments for other systems modes of the microscope can also be loaded by moving the appropriate labels to the Selected list and pressing apply 2 One of the control pads or z axis or tilt buttons is unresponsive Re initialize the pad by unplugging the USB cable from the back of the PC and re inserting it The right plug connects to the right panel left to the lef...

Страница 19: ...it should be visible in the back focal plane when you return to SA mode diffraction 4 Images contain black specks ghosts or other artifacts Make sure that both dark and gain references are being applied to the image Collect new references if necessary see section VI step 3 on pages 15 16 5 The stage or beam shift trackball is unresponsive If other controls on the same pad function normally then tr...

Страница 20: ...re present There are several possible causes of specimen drift The following may reduce it a Lightly tapping on the end of the sample holder rod can cause it to settle in the goniometer reducing drift b Move to a different area of the sample Damaged regions of a support film will often move as they are subjected to the electron beam In this case the sample itself is moving and viewing a more stabl...

Страница 21: ...he door open talking or large groups present in the instrument room will inevitably produce thermal and acoustic variations that will result in specimen drift Avoid these situations whenever possible 9 Other problems If the software is behaving unexpectedly you may close and restart the user interface and Digital Micrograph Logging out and back in may also resolve some problems Do not restart the ...

Страница 22: ...each instrument is FEI T12 Shepherd TEM T12 umn edu FEI FEGTEM Shepherd F30 TEM F30_Shepherd umn edu FEI Cryo FEGTEM NHH NHH F30 TEM F30_NHH umn edu Messages sent to the mail list will be distributed to everyone on the list Some uses for the mailing list include To subscribe unsubscribe Email addresses at umn edu can subscribe automatically through listserv umn edu To subscribe non umn edu address...

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