What does electron energy loss spectroscopy reveal?
Electron energy loss spectroscopy (EELS) is a characterization technique to measure kinetic energy change of electrons after inelastic interactions with materials, which provides structural and chemical information of the materials studied.
What is energy loss function?
Energy-loss function, defined as Im[-1/ ε(q,ω) ] as a function of momentum transfer ℏq and energy loss ℏω , characterizes inelastic scattering process. The dielectric function ε(q,ω) in energy-loss function reflects the response of a solid to an external electromagnetic perturbation.
What is the difference between EDS and EELS?
In an EDS spectrum, we see sharp peaks corresponding to the characteristic X-rays emitted by the atoms of the different elements present in the sample. EELS looks at the energy distribution of the electrons that have been inelastically scattered while passing through the sample.
What is a zero loss peak?
A sharp peak with an energy loss of 0 (zero) appearing in an EELS spectrum. The “zero-loss peak” is composed of no-scattered electrons and elastically scattered electrons. In a real spectrum, the peak shows an energy broadening (less than 0.7 eV) due to the energy spread of the incident beam.
What is electron energy?
The energy of an electron is of the same order of magnitude (is in the same range) as the energy of light. The lines in the spectrum of an element represent changes in the energy of electrons within the atoms of that element. The energy of an electron depends on its location with respect to the nucleus of an atom.
What is ionization edge?
From Wikipedia, the free encyclopedia. An absorption edge, absorption discontinuity or absorption limit is a sharp discontinuity in the absorption spectrum of a substance. These discontinuities occur at wavelengths where the energy of an absorbed photon corresponds to an electronic transition or ionization potential.
Why is AES more sensitive than XPS?
AES is a technique often described as more sensitive than XPS. Because the mean free path changes with the electron kinetic energy (see IMFP grapher), the depth of analysis will be smaller in AES than in XPS in the case of a carbon containing specimen.
Why are XPS and AES surface sensitive spectroscopies?
Sensitivity for most elements is better with AES than with XPS because a highly intense focused beam can be obtained with electrons but not with photons. Sensitivity is increased with a more intense beam.
How do electrons lose energy?
According to current theory electrons are arranged in electron shells around the nucleus, where each shell has a different discrete energy level. Then, as they lose energy by emitting photons, they might move back to the second energy level shell or even to the first energy level shell.
Why do electrons drop energy levels?
When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.