EFTEM SI Workflow

The preparation steps for EFTEM spectrum imaging (SI) are almost identical to EFTEM mapping.

1. Always start with a well-prepared sample.

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

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

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

5. Adjust the sample height to achieve coarse focus.

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

7. Operate TEM in EFTEM or Gatan imaging filter (GIF) lens mode to ensure a stable projector lens crossover.

8. Align the ZLP and focus the spectrometer.

9. Focus and carefully stigmate the image while observing the image on the GIF camera.

10. Offset the energy to obtain incoherent imaging conditions (typically 400 eV offset and 50 eV slit).

11. Optimize illumination intensity.

12. Carefully refocus incoherent images at energy loss.

You are now ready to set your mapping preferences for EFTEM spectrum imaging acquisition.