Instructions for Tecnai a brief start up manual

Transcription

1 Instructions for Tecnai a brief start up manual Version 3.0, Manual of Tecnai 12 transmission electron microscope located at Aalto University's Nanomicroscopy Center. More information of Nanomicroscopy Center at 1. Start up procedure 1. Turn ON monitors 2. Login: Ctrl+Alt+Del; Username: user; Password: Tecnai 3. Open and fill user s log 4. Open Gatan Digital Micrograph software and Tecnai User Interface software 5. Check that the window glass of the viewing chamber is protected by the black rubber disk 6. Fill the cold-trap liquid nitrogen dewar. If the 35L dewar is empty, fill it from the 230L dewar near the service corridor. 7. Check that High tension is ON i.e. the button is yellow. (If the button is grey with a black text, simply click it; if the button is grey with a grey text, in that case push high voltage on from the HT button on the panel close to the camera chamber) 8. Switch on the filament; heating takes ca. 4 8 minutes 9. Now the microscope is ready for operation. IF YOU ARE NOT ABSOLUTELY SURE HOW TO REMOVE OR INSERT THE SAMPLE HOLDER, READ CAREFULLY THE FOLLOWING INSTRUCTIONS!!! 1

2 2. Shut down procedure 1. Lower the fluorescent screen 2. If you were using nanoprobe, diffraction, HV other than 120kV, dark field etc. put the microscope back to standard operation mode and check that it is properly aligned in normal mode (standard operation mode = microprobe, 120kV, bright field) 3. Set the magnification to Spread the illumination so that it roughly fully covers the whole screen using the Intensity button on the panel, turn clockwise 5. Reset the holder (from workset Search Stage Control Reset Holder) 6. Take out the objective aperture (and also selected area aperture if used) 7. Filament OFF (Setup click Filament) 8. Close column valves 9. Cover the viewing chamber glass with the black rubber disk 10. Take sample holder out and remove your samples out from the holder 11. Put empty sample holder back into the microscope 12. If the next user is coming (for sure) within 4 hours add more liquid nitrogen to the cold trap Otherwise: Remove the dewar and start the cryo cycle (check settings: start after 1 min and duration 120 min). (Vacuum Cryo Cryo cycle) 13. Close the Tecnai user interface and (save settings) and close Gatan Digital Micrograph software 14. Fill the log 15. Log out 16. Turn off the monitors 17. CLEAN the tables etc. 2

3 3. Sample holders Goniometer (the place where the sample holder is in the microscope) and the sample holder itself are almost the only things which get broken quite easily therefore handle holders with some care they are also expensive: the standard holder is ca and the cryo holder is ca If you are not absolutely sure how to insert the sample holder, watch the demo movie and/or ask for help Do not touch holders with your bare hands. USE GLOVES! The grease from your fingers will contaminate the microscope vacuum system and also cause sample drifting. Do not touch the area between the o-ring and the tip even with the gloves How to remove holder from microscope 1. Check that the column valves are closed 2. Workset Setup vacuum Col. Valves closed button (this button should be yellow when valve is closed) 3. Holder can be removed during the filament heating and also when Filament is ON In practise 1. First pull the holder backwards until it stops at the same time by leaning with your fingers towards the blue disk 2. Then rotate the holder clockwise without pulling (IMPORTANT!!!) anymore 3. Then by leaning with your fingers towards the goniometer hold on to the holder and carefully push (IMPORTANT!!!) holder with your fingers backwards, because at this stage the airlock vacuum will give up and the holder will be released. Do not pull the holder out pulling will cause holder to move suddenly very fast and this may break the holder and/or goniometer Do not use too much force, it will only break things. Do not hesitate, i.e. use continuous movement 3

4 3.3. How insert a holder into microscope If you are not absolutely sure how to insert the sample holder, watch the demo movie and/or ask for help 1. Open vacuum overview window before you insert the sample holder to the microscope 2. Insert the sample holder so that the pin in the holder is directed with the 5 o clock line in goniometer and push the holder to the airlock. When you feel that the holder touches the cylinder inside the goniometer, it still may move inwards about 1.5 cm. 3. Then make sure that the vacuum pump starts to pump the airlock > red light will go on in the goniometer > See the vacuum overview window valve V8 should open about after 5 60 seconds. > Also make sure that the airlock vacuum level is really getting better (observe the decreasing pressure P2 vacuum gauge; vacuum overview window). The pump should run 40 seconds after the opening of valve V8, you can see the remaining time at the vacuum overview window. > If the countdown doesn t start or if the vacuum level won t get better, take the sample holder out and try again. 4. The red light goes out when the airlock is pumped and V8 closes. Then immediately rotate the holder counter clockwise until the vacuum starts to suck the holder in. When the vacuum starts to suck the holder in, hold it back so that it does not move too fast. > Note: (Red light does not go out if holder type is not selected if asked, however at the moment setting should be so that holder selection is not needed). 5. Cover the viewing chamber window with black rubber disk and add more liquid nitrogen to the cold trap if necessary 6. Gun/Col vacuum reading should be below 25 and then you can open column valves (and remove the window cover) and microscope should be ready TIPS: Vacuum with the holder will reach normally 6, below 25 is safe If the vacuum crashes: stop and start the vacuum again using the Vac push button on the right side of the camera chamber (i.e. you have to press button twice) 4

5 4. Inserting grids to four place specimen holder Do not touch holders with your bare hands USE GLOVES!!! Do not touch the area between the o-ring and the tip even with the gloves. The grease will contaminate the microscope vacuum system. Grids are first put to the correct places in the holder by sharp tweezers. Then a circlip is taken with the tool and seated on top of the grid, so that it fastens the grid on its place. The seating of the circlip can be ensured by gently pushing it with the other tool. The place number one is the outmost in the four place holder. The selected grid is indicated in the holder as white spots, for example the grid number four = four white spots. Circlips and tools for handle them. Places for grids. 5

6 5. Aligning The microscope is usually quite stable. Do the alignment only if you notice the alignment is not good enough. (Objective aperture needs to be centered always and usually stigmators need some tuning and gun tilts if intensity is low.) 5.1 Check before aligning that: 1) Objective and selected-area apertures are OUT Condenser aperture (should be always IN pin pointing left) Objective aperture (OUT when pin pointing right) Selective area aperture (OUT when pin pointing right) 2) Objective lens current is in optimal setting (= press eucentric focus button) 6

7 5.2 Gun tilt (Aligning beam to optical axis) 1) Find the empty area without sample 2) Select ca x magnification and spot size 3 3) Focus using the Intensity button and center the beam using trackball on the left panel 4) Spread the beam so that the beam almost fully covers the fluorescent screen (turn clockwise Intensity button) 5) Select Gun tilt from workset Tune and Direct Alignments window 6) Maximize the beam intensity using multifunctioning buttons OR minimize exposure values on the screen 5.3 Gun shift 1. Select Gun shift from the Direct Alignments window 2. Select ca x magnification (and empty area without sample) 3. Focus the beam using the Intensity button and center the beam using the trackball on the left panel 4. Select spot size 9 (Button R3). If the beam disappears, select larger spot (smaller number) first and center that first and then go to spot size Center the beam using trackball (beam shift) on the left panel 6. Change to the spot size 3 (Button L3) 7. Center the beam using multifunction buttons 8. Repeat the steps 4 to 7 until the beam stays in the center at both spot sizes 9. Usually 1 or 2 repetitions is enough 5.4 Adjust Beam tilt pivot point X and Y USUALLY YOU CAN SKIP THIS ALIGNMENT!!! But it is very easy to do 1. Focus the beam 2. Select Beam tilt pivot X from the Direct Alignments window 3. Adjust the values using the multifunction buttons (both) until the beam doesn t move 4. Beam does not have to be centered 5. Then repeat same for Beam tilt pivot Y 7

8 5.5 Adjust Beam shift USUALLY YOU CAN SKIP THIS ALIGNMENT!!! But it is very easy to do 1. Select Beam Shift from the Direct Alignments window 2. Center the beam using the multifunction buttons (or left trackball) 3. Press Done 5.6 Condenser aperture centering USUALLY YOU CAN SKIP THIS ALIGNMENT. DO if you change the aperture size or if you notice that is misaligned (misaligned = beam intensity does not spread symmetrically when beam is over/under focused) 1. Select ca x magnification 2. Focus intensity of beam using the Intensity button and center beam using the trackball of the left panel 3. Then spread the beam (clockwise the Intensity button) until it almost fully covers the screen 4. Center the beam by adjusting the condenser aperture (the top one) with screws in the center and on the right 5.7 Setting sample to the Eucentric height DO THIS ALWAYS! 1. Find the sample and magnification x is quite OK. 2. Spread the beam with the Intensity button; over the fluorescent screen 3. Press L1 button (that will activate the alpha wobbler) 4. Minimize sample movement by adjusting the height of the sample using the Z-axis pushbutton on the right panel 5. Unselect Wobbler by pressing L1 button again 5.8 Rotation center (voltage or current center) 1. Find the sample and some small details which you can magnify up to x (e.g. small hole, sham sharp point etc.) 2. Select magnification over x (preferably ~ x) and focus the sample 3. Select Rotation center from the Direct Alignments window. Now Focus Step -function i.e. the lower rim of the Focus is Focus Wobbler Amplitude 4. Minimize the amplitude by turning focus step counter clockwise i.e. until the sample doesn t wobble 5. Check the sample focus again; use the upper rim of the Focus button. 6. Increase the focus wobbler amplitude by turning Focus step clockwise (1 or 2 steps) so that you can see the focus to wobble from underfocus to overfocus 7. Adjust Rotation center using multifunction buttons so that the sample movement is minimized (you may need to adjust beam using trackball during alignment) 8. Press Done 8

9 5.9 Insert objective aperture and center it DO THIS ALWAYS! NB! Never let the direct diffraction beam go to the camera! (But anyway we are not using camera here..) 1. Set the magnification to ca x 2. Spread the beam (turn clockwise the Intensity button) 3. Select the Diffraction mode from the right panel 4. Camera length approx is OK 5. Focus the diffraction pattern, use the binocular If the intensity is too high or you cannot focus the diffractions pattern. Insert selected area diffraction aperture and center it (size 2 or 3) 6. Put the objective aperture in (typically number 1 or 3); the objective aperture is the middle one of the apertures 7. Center the objective aperture with respect to the diffraction pattern using the screws of the objective aperture in the center and on the right 8. Deselect the diffraction mode NB! Never let the direct diffraction beam go to the camera! If diffraction is going to the camera remove Diffraction mode or insert screen with R1 button 9

10 5.10 Objective stigmators If you have carbon film grid use carbon film to get an amorphous scattering otherwise use your sample 1. Use Live-FFT. Take ca x magnification 2. Observe the rings at the Live-FFT window. It can be seen at a slight underfocus (Image A and C). If the peak is like ellipse (Image A), stigmators has to be adjusted. 3. Select Workset Tune Stigmators Objective. First copy the current active settings to other memory position by using the mouse right button (example copy 1 to 2) so that you can recover the values if everything goes wrong 4. Then correct stigmators by using multifunction buttons. (First try to get symmetrical spherical pattern when sample is underfocused (Image C) and then try to minimize patter when sample is focus. (Image D) Snap shots of live-fft imaged of carbon film. Micrographs A and B taken with misaligned object stigmators and C and D with aligned ones. A and C taken at sample underfocus and B and D at sample focus. 10

11 Routines performed after sample change Set sample to eucentric height. Hints and notes Save all the micrographs to the Z-disk. Setting Int Zoom at the Beam Settings window will make intensity to be constant when the magnification is changed. Wobbler on the right panel can be used for focusing, especially at low magnifications. When the sample is in-focus you see only one image. Note also that low magnification calibration is very sensitive to focus. If your sample is out of focus magnification will be quite different. Fluorescent screen lift is R1 button on the right hand panel. Troubleshooting If hand panel hangs, detach and attach the usb-cable from the panel. This usually solves the problem. If vacuum system fails when you insert or extract the sample holder. Stop and start vacuum again using the Vac push button on the right side of the camera chamber. In case of any other problems call (Janne Ruokolainen) If you need to restart the computer After the restart: Start the vacuum. "Vac" button on the right side of the camera chamber. Select the high tension 120 kv and the emission current step value 11