[Wien] Difference among XAS, ELNES and EELS

[Guillaume Radtke]

Hi BoKang,


XAS stands for X-ray Absorption Spectroscopy and EELS for Electron  
Energy Loss Spectroscopy. These
two techniques are used to probe the unoccupied electronic states of  
condensed matter and are actually
very similar. In the first one, you use X-rays (in the second one,  
electrons) to observe electronic transitions
from a core state to the unoccupied states of the solid. These  
transitions are observed on the spectra at
specific energies corresponding to the binding energies of the core  
electrons and form ionization edges.
The intensity variations observed near the edge onset are called  
Energy Loss Near Edge Structures (ELNES)
or X-ray Absorption Near Edge Structures (XANES) and are related to  
the site- and symmetry- projected
density of states, that's the reason why it can be efficiently  
calculated with band-structure codes
like Wien2k (at least for the K edges 1s -> p PDOS and some L23 edges  
2p -> s +d PDOS)

For details on EELS see : R.F. Egerton, EELS in the Electron  
Microscope (Plenum, New York, 1986).

Guillaume.









Le 4 déc. 07 à 14:05, 波 康 a écrit :

> Dear wien users,
>
>         Using WIEN2k code, we can calculate XAS and ELNES. I am  
> very confused, what's the differences among XAS, ELNES and EELS.  
> Could anyone tell me?
>
>        Any reply will be appreciated!
>
>                                                BoKang
>
>
>
> 进入雅虎游戏嘉年华，赢取液晶显示器！
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