Two-beam Kinematic Electron Scattering/Diffraction
- Practical Electron Microscopy and Database -
- An Online Book -

http://www.globalsino.com/EM/  



 
This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

=================================================================================

Starting from the two-beam kinematic diffraction theory, when the TEM sample thickness is very small, the extension (H) of the reflection in reciprocal space is very large. Therefore, Q is much smaller than πH so that the two-beam dynamical scattering theory can be approximated by two-beam kinematic diffraction theory, which suggests the intensity of an <hkl> diffracted beam given by,

         two-beam kinematic diffraction theory ------------------------ [2713a]
         Two-beam dynamical diffraction conditions / first Bethe approximation in TEM Measurements ------------- [2713a]
where,
         I0 -- The intensity of the incident electron beam,
         S -- The illuminating area by the incident electron beam,
         Φhkl -- Fourier coefficients of an electrostatic potential,
         Fhkl -- The structure factors,
         A -- The thickness of the crystal in the TEM specimen,
         H -- The extension of the reflection in reciprocal space,
         σ -- The interaction constant between the incident electrons and specimen,
         Θ -- The half of the angle between the transmitted and scattered electron beams,
         ξhkl -- The extinction distance.

In the kinematic theory, the integrated reflection coefficient is given by,

         Two-beam dynamical diffraction conditions / first Bethe approximation in TEM Measurements ------------- [2713c]

where,
         L -- The Lorentz factor in unit of length.

 

 

 

=================================================================================

The book author (Yougui Liao) welcomes your comments, suggestions, and corrections, please click here for submission. If you let book author know once you have cited this book, the brief information of your publication will appear on the “Times Cited” page.