The SAED pattern, we obtained from HRTEM shows the interplanar spacing (d) that corresponds to a higher 2theta value than the Powder crystal X-ray diffraction pattern for the same organic polycrystalline material. But that 2theta is not present in our PXRD.
If is it possible to get a higher order of diffraction (n>1) then what could be the reason. Please explain it.
Deepak Rase
Check out useful links
https://www.researchgate.net/post/How_can_I_analyze_The_SAED_pattern_generated_by_HRTEM_and_how_can_I_calculate_the_d_spacing_from_it_and_what_are_the_parameters_I_need_know
https://www.researchgate.net/post/Is_it_possible_to_get_amorphous_nature_from_the_SAED_pattern_diffused_rings_and_lattice_fringes_from_the_TEM_image_for_the_same_sample
https://www.tandfonline.com/doi/pdf/10.1080/10473289.2003.10466133
In theory, it is possible to get higher order diffraction maxima in most experiments. But, practically compared to the central maxima, the higher order maxima have negligible intensity. For single slit it is, 1 : (4/9π2) : (4/25π2) : ... ≈ 1 : 0.045 : 0.016 : ... and in other cases, the values may vary a bit. But, unless the central maxima is extremely intense, it is difficult to detect higher order patterns.
Are you sure you are not experiencing Moiré fringes in your sample? When two similar patterns are overlapped we could see something that looks like interference fringes from diffracted planes. However, it is in a n*d order of length of the overlapped crystalline planes.
Good luck.
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