Stanford Titan Daily Operation Manual
- Image Cs corrector
- Gatan Tridiem 866 Imaging Filter (for EFTEM and EELS)
- HAADF detector (outer collection angle capped at 70mrad because of ETEM differential pumping apertures)
- BF/DF STEM detectors
- Magnetic biprism (for electron holography)
- Dual tilt axis tomography holder (for electron tomography)
- SuperTwin objective pole piece
- Environmental cell
- High brightness gun
- CCD camera
- Fast frame rate camera (runs on a separate computer)
Vacuum and High Brightness Gun Safety:
- Always fill the LN2 dewar at the start of your session. Top up once every ~ 4 hours.
- Always check that column valves are closed.
- Open column valves when (1) the specimen holder is inserted in the microscope column and (2) the octagon reading is <18 log.
- The extraction voltage for the high brightness gun is kept constant at 4700V. Do not change this.
- Users operating the microscope in filtered (monochromated) mode can only use the gun lens in decelerating mode.
- Check that the specimen holder O-rings are free of dust before inserting the holder into the microscope.
- Plasma-clean your sample and specimen holder for 2-3 minutes before inserting the holder into the microscope.
- For samples on carbon film, you can plasma clean the sample for about 10 seconds.
- Last user of the day should run cryo cycle.
Titan Daily Operating Instructions: Start-up and Shut Down
1. Start Up and Shut Down
- Start the software in the following order:
- Titan User Interface
- Cs image corrector
- Filter Control (GIF)
- Digital Micrograph
- Check that the vacuum readings (in units of log) are:
- Gun: 1 Log
- Liner: < 16 Log
- Octagon: < 18 Log
- Check high tension and extraction voltage are ON
- Ensure that the column valves are closed.
- Click “Turbo on” to start the turbopump.
- Load your sample in the double tilt holder. Check the O-ring on the holder for dust/contamination.
- Place sleeve over the end of the loading tube and carry the holder in the loader to the plasma cleaner.
- Plasma clean specimen holder (with sample).
Daily Shut down
- If you are at different modes, please return to TEM mode or microprobe mode (Free control -> C3 off -> microprobe) and be at ~ 5600X magnification
- Reset holder, and remove specimen holder
- The last user for the day should run cryo cycle.
2. Sample Exchange Procedure
* Always wear gloves when handling the specimen holder *
- Check that the x, y, z,a, b = 0. If not, reset holder.
- Position pin of the specimen holder at the 5 o’clock position, insert to first stop which is halfway.
- Check that the red light is on and that the pre-pumping phase is activated. Prepump is five minutes.
- Choose the appropriate holder (FEI double tilt). Click enter.
- When asked by the software to connect the second tilt cable, connect the tilt cable and click enter. Red light will stay on after prepump if this is not done.
- After the pre-pumping phase (red light goes out, also check the valve VIIt is closed), hold the specimen holder firmly and rotate counterclockwise till reach a stop. Keep a firm hold on the holder and let it slide gently the rest of the way into the column.
- Check that the octagon value is <18 log before you open column valves.
Sample Exchange Procedure
- Reset the holder. Make sure that x, y, z, a, b = 0 (the compustage red light should be off)
- Disconnect tilt cable (for double tilt holder)
- While pressing the purple surround on the goniometer, carefully pull holder out until stop.
- Turn clockwise until stop.
- Still pushing against purple surround, carefully remove holder.
- Place the holder back into loading tube/dock.
- Click the “Turbo pump” button
3. Saving Files
- All data should be saved on the Network Drive and retrieved on the buffer computer in the Titan remote room. Refer to instructions on “Mapping and Saving Files on the Network Drive” to set up the network drive for your account.
- You are not allowed to insert any USB sticks on the Titan computers.
4. Running Cryo Cycle
- Remove LN2 dewar, empty excess liquid nitrogen back into larger dewar for safety. Leave LN2 dewar facing down in the box at the corner of the Titan room.
- Place paper towels on dewar stage.
- On the setup page of Titan User Interface, open the right flap of the vacuum window and choose the cryo tab.
- Cryo cycle should be set to start after 5min. Set the duration of the cryo cycle to be 300min.
Titan Daily Operating Instructions: Pre-Setup
Pre-Setup (with a pre-aligned mode)
- Insert a specimen with a sufficiently large amorphous area. E.g.: gold/carbon cross-grating sample.
- Be at <10,000X magnification.
- Check that the octagon reading is < 18 log before opening column valves.
- Make sure that you can see the beam. If you cannot see the beam, try the following:
- Select largest C1, C2 and C3 apertures.
- Check which mode the Titan is in (STEM or TEM mode etc)
- Move sample with joystick to make sure that the sample is not blocking the beam.
- Select “TEM” under Beam Settings (Flap up menu). Choose TEM or Free Control -> C3 off -> Microprobe
- Load the appropriate alignment file (Align tab -> Flap out -> File)
- Load the monochromator file. (Mono tab -> flap out -> File)
- Press the “Normalize” button under the Mono tab.
- Press “eucentric focus” and “Reset defocus” and move the specimen with the z-axis to eucentric height. Note that for the cross-grating sample, the eucentric height is at approximately -200mm.
- If the edge of the beam appears jagged, this means that the monochromator has drifted. Adjust the beam using the “monoshift X” and “monoshift Y” controls under the “Mono” tab.
- Set optimal C2 lens current and gun lens value:
- Go to Beam settings (Flap up menu) -> Free Control -> C3 off -> microprobe mode.
- Change C1 aperture to “Slit 1”
- Perform “Slit Wobbler” (under “Mono” tab”). Adjust the intensity knob until the slit movement is minimized. This sets the C2 lens current to its optimal value
- De-select “Slit Wobbler”. Change C1 aperture back to 2000mm
- Under the “Mono” tab, select “Focus”. Use the intensity knob to bring the beam to crossover. Check that the reading under the “Focus” button is zero. If not, press “store” to reset the value to zero.
- Continue to use the intensity knob to set the “Focus” value in the mono to ~ +35 to +40 (until the beam completely covers the aperture). This gives the optimal illumination and gun lens for parallel illumination mode.
- De-select “focus” under the Mono tab
- Correct condenser astigmatism at ~ 100kX magnification.
- At ~ 100kX, perform the following direct alignments (Under the “Align” -> “Direct Alignments” tab)
- Align beam shift
- Beam tilt pivot points
- Rotation centering
- Repeat direct alignments at ~ 300kX magnification.
- Make sure that the objective stigmator and the diffraction stigmator values in Titan User Interface are set to zero (Stigmator tab). If the obj stig values are non-zero, either reset the stigmator values, or pick the column where the stig X and Y values are both zero.
- Lift the screen and view an image of the sample, and its live FFT, on the CCD camera. Go to slightly underfocus using the z-height of the specimen. Keep defocus value at 0 (This is because the corrector is linked to the objective lens and therefore it is best to tune the corrector at the optimal objective lens current value, which is the value at eucentric focus).
- For tuning the image corrector, proceed to instructions on “Cs Image Corrector Tuning”