Elastic backscattering

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

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...

A correction for matrix effects is usually required. Difficulties in PIXE quantitation may be relieved by complementary information from RBS [290], or FTIR and elastic backscattering (EBS) analysis [291], FTIR can give a rough estimation of the elemental composition, while EBS or RBS can deliver information on the major-element composition. 

EBS Elastic backscattering ESCI Electrospray chemical ionisation... 

Fig. 11. Channeling data for the 111 plane (Marwick et al., 1987, 1988), showing data for the nuclear reaction with 2H atoms in the sample and the yield of elastically backscattered 3He ions. The central peak in the 2H scan is important evidence that the 2H atoms occupy bond-center sites. The solid line is a fit to the data, as described in the text.

Figure 6.17 shows a schematic of the LEED system. The sample is bombarded through the left by a beam of electrons. Only radiation or electrons (remember the wave nature of matter ) with the same energy as the incident beam are detected. These electrons are called elastic backscattered electrons. The detection system is a fluorescent screen placed in front of the sample. Holding the screen at a large positive potential accelerates the electrons. Once they reach it, they excite the phosphorus in the screen, marking it with bright spots characteristic of the diffraction pattern. Finally, a camera in front of the screen records the diffraction pattern. 

The use of elastic backscattering, which is the primary technique for energetic ion beam analysis, is the normal method of choice when it will produce satisfactory results. Some other ion beam techniques which may be useful in supplementing backscattering in specific cases will be discussed later in this paper. 

Disappearance potential spectroscopy DAPS The EAPFS cross-section is monitored by variations in the intensity of electrons elastically backscattered from the surface. Electronic structure... 

When slow electrons (energy less than about 300 eV) are directed normal to a surface, only a small fraction is elastically backscattered. The remaining electrons are backscattered after losing energy, or are absorbed in the crystal. Only the elastically scattered electrons, about 1 % of the incident number, produce the diffraction patterns with which we are concerned here. 

In the self-consistent approach of McRae (54, 55, 58, 59,177) and others (43, 68) the complete multiple diffraction problem, with attenuation of the wave by elastic backscattering alone, has been solved in self-consistent fashion for certain idealized cases. Inelastic losses were not included in the theory at all. However, in the recent work of Duke and Tucker (179) and of Jones and Strozier (66) inelastic absorption is treated as the dominant effect, and this is nearer reality when considering the LEED problem at all but the lowest energies. 

Cox R P, Leavitt J A and McIntyre L C Jr 1995 Non-Rutherford elastic backscattering cross sections Handbook of Modern Ion Beam Materials Analysis ed J R Tesmerand M Nastasi (Pittsburgh, PA Materials Research Society) ch A7, p 481... 

The size of these deviations fid E) from the atomic absorption fiod E) amounts to roughly 10% of the edge jump A d, which describes the difference between the mean absorption at energies above the edge and below the edge. This 10% corresponds to the part of elastically backscattered electrons. The other part of the excited electrons experiences forward scattering or are lost by inelastic scattering processes. They do not contribute to variations in the absorption. 

SIGMACALC Gubrich AF (1996) software for non-Rutherford elastic backscattering cross-sections http //www.ionbeamcentre.com/sigmacalc/... 

In all practical circumstances the characteristic angle that controls the angular profile near 6 = 0 (table 1) is quite small, and in reflection geometry the small angle loss must be accompanied by an elastic reflection in order for the electron to be detected in the spectrometer (fig. 1). Elastic backscattering is much more probable than the inelastic process, and furthermore the elastic momentum transfer is taken up by the whole crystal. 

Why is it possible to obtain information on atmospheric gaseous pollutants using laser radar although elastic backscattering from particles is primarily observed ... 

Low-energy electron diffraction LEED Elastic backscattering low-energy electrons Atomic surface structure of surfaces and of adsorbed gases... 

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