Basic STEM alignment

Owned by gys37319
Last updated: Nov 28, 2017

Do not attempt to do anything you have not been trained to do by ePSIC staff.

  1. At the start of the day perform a high flash and run up the emission.
  2. Open the beam valve and check there is a beam on the large phosphor screen.
  3. Ensure that ‘Ronchigram’ is selected on TEMCentre and that scanning is stopped on digital micrograph.
  4. Check objective lens is set to standard defocus.
  5. Bring sample to eucentric height (infinite magnification).
  6. Set camera length to 20cm.
  7. Manually correct for coma and two-fold astigmatism in the Ronchigram on the focus phosphor screen or camera.
  8. Centre the Ronchigram using the projector lens deflectors.
  9. If necessary run the corrector (CEOS for E01, COSMO for E02)
  10. Insert the required condenser lens aperture and centre to the flat area of the ronchigram.
  11. Select the required camera length.
  12. Using the projector lens deflectors centre the bright field disc to the centre of the detectors.
  13. Deselect ‘Ronchigram’ in TEMCentre.

  14. In TEMCentre, select the required detectors for imaging.  

If you leave the microscope please ensure the beam valve is closed.

If you leave the microscope for an extended period of time please:

  • Close the beam valve.
  • Run down the emission.

On returning to the microscope: 

  • Perform a low flash.
  • Run the emission back up.

If your emission current drops significantly during your session you can restore to 15μA by following the above procedure.

Do not attempt to flash the tip while the emission is on.