
DielectricConstant Determination by EELS
 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.

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As discussed on page4360, the energyloss process of incident electrons can be treated by the dielectric response of the electrons. Therefore, the EELS contains information about the dielectric constant ε. The singlescattering spectrum intensity I is given by,
I = I_{0}(t/k)Im(1/ε)ln[1 + (β/θ_{E})^{2}]  [4290]
where,
I_{0}  The intensity in the zeroloss peak.
t  The specimen thickness.
k – A constant incorporating the electron momentum and Bohr radius.
KramersKronig analysis is normally used to obtain the real part of the dielectric constant from the imaginary part (Im) in Equation 4290. In such evaluation, deconvolution has to be performed because a singlescattering spectrum is needed. The lowenergy plasmon part of the energyloss spectrum to ~25 eV corresponds to an optical analysis of the dielectric response from the visible to the ultraviolet.

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