Basic Preparation

Below are common steps to prepare your sample and system for an EFTEM experiment.

  1. Always start with a well-prepared sample.

    1. For elemental mapping, sample thickness should be between 0.5 – 15 mfp (0.5 – 2.0 for edges >1 kV)

  2. Align the TEM; gun tilt, condenser alignment, and optical axis alignment are critical.

  3. For mapping, a high beam current is desirable.

    1. If your sample is not beam sensitive, use the largest aperture and spot size

  4. Set the TEM objective lens current at its optimal value.

  5. Adjust the sample height to achieve a coarse focus.

  6. Center an appropriate objective aperture to limit chromatic blurring.

  7. Operate the TEM in GIF or EFTEM mode to ensure a stable projector lens crossover.

  8. Focus and carefully stigmate the image while you observe the image on the Gatan imaging filter (GIF) camera.

  9. You are now ready for EFTEM imaging or spectrum imaging (EFTEM SI) acquisition.

If these symptoms occur when you switch to the GIF mode on your TEM, the mode is not correctly set up.

  • The region of interest center on the GIF camera in GIF mode is not the same as conventional TEM mode

  • The GIF mode image is significantly out of focus when you compare to the conventional TEM mode

  • Image is cut off or not visible on the TEM view screen when you enter GIF mode

  • Diffraction patterns are not centered in GIF mode

To correct these abnormalities, please consult the TEM documentation or service organization for the appropriate settings.