XPS. X-ray Photoelectron Spectroscopy. ESCA Electron Spectroscopy for Chemical XPS, also known as ESCA, is the most widely used surface analysis. Etude par spectroscopie de photoelectrons (XPS) de la surface de profiles a au cours de différents traitements, par spectroscopie de photoélectrons (ESCA ou. La spectroscopie des photoélectrons induits par rayons X est une technique Au cours d’une analyse XPS, des photons (Al Kα ou Mg Kα) sont envoyés sur.
|Published (Last):||27 July 2004|
|PDF File Size:||15.76 Mb|
|ePub File Size:||16.98 Mb|
|Price:||Free* [*Free Regsitration Required]|
Through the photoelectric effect, photoelectrons are ejected from the surface illuminated with a X-ray source. The different chemical states of oxygen bound to silicon and to titanium are observable in the local spectra reconstructed from the image series.
Spatially resolved surface chemical state analysis down to 50 nm.
Thus, the electrons interact with the spectroscoipe field on the top of sample surface. The analyser allows high transmission imaging at kinetic energies far spfctroscopie threshhold without sacrificing the lateral and energy resolution of the instrument.
B 60, Spatially resolved surface chemical state analysis down to 50 nm XPEEM can provide the elemental map of preferential grafting of p-MAN polymer on a gold patterned silicon substrate. Hoffmann, Shao-Ju Shih, D. In addition, synchrotron-based XPEEM is one of the most powerful spectro-microscopic techniques for studying the chemical and electronic structures of thin film systems, combined with the tunability and polarizability of x-ray sources and high brilliance of synchrotron radiation sources.
The use of a novel speectroscopie of a photoelectron microscope in combination to an imaging energy filter for momentum resolved photoelectron detection.
X-ray Photoelectron Spectroscopy (XPS)
XPS, X-ray Photoelectron Spectroscopy is a specroscopie analysis technique which provides both chemical and electronic properties. Compared with the first concept, it is simpler for two reasons. High spatial and energy resolution can be achieved by the fully energy filtered XPEEM, the spatial resolution down to a few tens of nanometers have been achieved. Thus successive zoom in the interested region or surface structure become simpler.
The second concept used in PEEM is presented by the system with pure electrostatic lens, as shown in leftside figure.
High transmission is particularly important especially for highest resolution imaging XPS with monochromated laboratory X-ray sources. Firstly, it avoids the intrinsic problem derived from the application of high voltage into sample.
Firstly, the imaging condition corresponds to the approximately Gaussian optics. Nb is studied using XPEEM for various grain orientations in order to characterize the surface chemistry with high spatial resolution. The lenses are specrroscopie. Details refer to O. The grain orientation is cougs by electron backscattering diffraction EBSD.
There are two advantages for having the very high electron energy in the column of PEEM. This technique allows the detection of virtually all elements present on the surface probing depth 1 to 10nm.
Details refer to B. The reflectivity is then considerably enhanced, while the transmission is very small. Most laboratory-based PEEMs use this concept. The sample is negative biased relative to the objective lens, typically kV, as illustrated in right side figure. The advantage of LEEM is the intensity of the beam, which permit the fast scan on the sample surface with high spatial resolution, and also the possibility of using special mode of microscopy, like the mirror electron microscopy MEM.
This allows us to study, for example, the distribution of the surface dipoles. The surface composition of polycrystalline Nb-doped strontium titanate SrTiO3: Figure shows a k -space image of Cu taken at the Fermi energy with an exposure time of 5 min excited with He I. They have characteristic binding energy which depends on the element, orbital and chemical environment of the atom.
Secondly, the optics are electrostatic: Together with a time resolved imaging detector, it is possible to combine spatial, momentum, energy, and time resolution of photoelctrons within the same instrument.
There are two basic PEEM conceptions, each of them are optimized according to its application. The small ring in the center is the Shockley surface state.
Study the spatial and momentum resolved electronic structure-directly band structure imaging. The potential of the sample is zpectroscopie ground, while the extraction lens is at a positive high voltage.
The electrons are decelerated till a limited kinetic energy so that it will be reflected before reach the surface of sample.
Stereographic plots are used to show the correlation between surface assigned to major orientation. Details refer to L. The surface Brillouin zone is marked by a black hexagon. The surface sensitivity is maximized by the use of soft x-ray synchrotron radiation SR.