Surfaces backscattering

Figure 8 (A) Surface backscattering yields from Pb(11 0) as a function of temperature. The bulk melting temperature Tm is indicated. (B) As for (A) but for the Pb(111) surface. (Reprinted with permission from van der Veen JF and Frenken JWM (1991) Surface Science 251/252 1 Elsevier.)...

LEED Low-energy electron diffraction [62, 75, 105] Elastic backscattering of electrons (10-200 eV) Surface structure... 

ISS Ion scattering spectroscopy [153, 154] Inelastic backscattering of ions (-1 keV ion beam) Surface composition... 

EXAFS Extended x-ray absorption fine structure [177, 178] Variation of x-ray absorption as a function of x-ray energy beyond an absorption edge the probability is affected by backscattering of the emitted electron from adjacent atoms Number and interatomic distance of surface atoms... 

Figure Al.7.12 shows the scattered electron kinetic energy distribution produced when a monoenergetic electron beam is incident on an A1 surface. Some of the electrons are elastically backscattered with essentially...

Heiland W and Taglauer E 1977 The backscattering of low energy ions and surface structure Surf. Sc/. 68 96-107... 

Taglauer E 1997 Low-energy Ion scattering and Rutherford backscattering Surface Analysis The Principal Techniques ed J C VIckerman (Chichester Wiley) pp 215-66... 

Rutherford backscattering spectrometry is the measurement of the energies of ions scattered back from the surface and the outer microns (1 micron = 1 pm) of a sample. Typically, helium ions with energies around 2 MeV are used and the sample is a metal coated silicon wafer that has been ion implanted with about a... 

Figure Bl.24.5. Backscattering spectrum of a thin Ni film (950 A) with near monolayers ( 30 x 10 at cm of An on the front and back surfaces of the Ni film. The signals from the front and back layers of An are shown and are separated in energy from each other by nearly the same energy width as the Ni signal.

The SEM can also be used to provide crystallographic information. Surfaces that to exhibit grain structure (fracture surfaces, etched, or decorated surfaces) can obviously be characterized as to grain size and shape. Electrons also can be channeled through a crystal lattice and when channeling occurs, fewer backscattered electrons can exit the surface. The channeling patterns so generated can be used to determine lattice parameters and strain. 

Within the last 5—10 years PIXE, using protons and helium ions, has matured into a well-developed analysis technique with a variety of modes of operation. PIXE can provide quantitative, nondestructive, and fast analysis of essentially all elements. It is an ideal complement to other techniques (e.g., Rutherford backscattering) that are based on the spectroscopy of particles emitted during the interaction of MeV ion beams with the surface regions of materials, because... 

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