Diffraction Mode:

This is obtained by intentionally excluding central beam and collecting all diffracted beams.

Figure 15.01: Typical diffraction pattern obtained for polycrystalline materials in TEM.

SAED pattern analysis for Indexing:
The SAED pattern can be analyzed using the following simple relation:

R d = L λ
L = ( R . d )/ λ

where, R - Diameter of the ring, d - d - spacing, L - Camera Length, λ - Wavelength of the e -beam.

Procedure to analyze the SAED pattern:

1) Find the camera length from the calibration sample.

2) Use the same camera length to identify various SAED patterns of unknown samples.

Determining unknown parameters for Camera length calculation?