=================================================================================
EELS measures the distribution of energies lost by incident electrons (typically 100–1000 keV) as they pass through a thin solid specimen (typically 0.5–50 nm).
Table 4716. Examples of TEM sample thickness used for EELS.
Sample Thickness Used |
Materials |
|
Electron Mean
Ffree Paths |
|
Reference |
10–30 nm |
Oxidic materials |
|
|
|
[1] |
|
|
|
|
|
|
|
|
|
|
|
|
For plasmon measurements, moderate thickness (t ~ λ) of specimen is normally used in order to reduce the surface plasmon contributions, which are non-negligible at small thicknesses t and to reduce plural scattering which are significantly gained at large thicknesses. Here, λ is inelastic mean free path (IMFP) of electrons.
Polycrystalline silicon sample was mechanically polished until less than 10 µm in thickness, and then ion milled with 3 keV Ar ions in a Gatan Model691 PIPS. The final thickness for EELS measurements of grain boundaries was 20 nm. [2]
[1] Optimization of the Signal to Noise Ratio in EFTEM Elemental
Maps with Regard to Different Eonization Edge Types
G. Kothleitner and F. Hofer, Micron Vol. 29, No. 5, pp. 349–357, (1998).
[2] Norihito Sakaguchi, Makito Miyake, Seiichi Watanabe and Heishichiro Takahashi, EELS and Ab-Initio Study of Faceted CSL Boundary in Silicon, Materials Transactions, Vol. 52, No. 3 (2011) 276.
|