Monoenergetic atomic beams

These experiments are performed in the apparatus previously described. The Ni(111) crystal is maintained at 46 K in an ambient atmosphere of 10" torr of methane. Under these conditions, a monolayer of molecularly adsorbed methane is present (ref. 9). A monoenergetic Ar atom beam, produced by the high... 

Helium atom scattering Monoenergetic beam of helium Gas-solid 1996HOF/TOE... 

J. V. Prodan, W.D. Phillips, H. Metcalf Laser production of very slow monoenergetic atomic beam. Phys. Rev. Lett. 49, 1149 (1982)... 

Prodan, J., Phillips, W., and Metcalf, H. (1982). Laser production of a very slow monoenergetic atomic beam. Physical Review Letters, 49, 1149-1152. 

If a beam of monoenergetic ions of mass A/, is elastically scattered at an angle 6 by surface atoms of mass Mg, conservation of momentum and energy requires that... 

LEIS Low-energy ion scattering [155-157] A monoenergetic beam of rare-gas ions is scattered elastically by surface atoms Surface composition... 

The hybridization of carbon atoms is the major structural parameter controlling DLC film properties. Electron energy loss spectroscopy (EELS) has been extensively used to probe this structural feature [5. 6]. In a transmission electron microscope, a monoenergetic electron beam is impinged in a very thin sample, being the transmitted electrons analyzed in energy. Figure 27 shows a typical... 

Figure 6.7 The principle of LEED is that a beam of monoenergetic electrons scatters elastically from a surface. Because of the periodic order of the surface atoms, electrons show constructive interference in directions for which the path lengths of the electrons differ by an integral number times the electron wavelength. Directions of constructive interference are made visible by collecting the scattered...

Monoenergetic beams of atoms are scattered from ordered surfaces and detected as a function of scattering angle. This gives structural information on the outermost layer of the surface. Atom diffraction is extremely sensitive to surface ordering and defects. 

A monoenergetic beam of electrons is used to excite atoms in the near surface region. As the beam energy is swept, variations in the sample emission current occur as the beam energy sweeps over the energy of an Auger transition in the sample. Also known as APAES. 

Monoenergetic photons excite a core hole. The modulation of the absorption cross section with energy at 100 - 500 eV above the excitation threshold yields information on the radial distances to the neighbouring atoms. The cross section can be measured by fluorescence as the core holes decay or by attenuation of the transmitted photon beam. EXAFS is one of the many fine -structure techniques. 

In photoelectron diffraction experiments monoenergetic photons excite electrons from a particular atomic core level. Angular momentum is conserved, so the emitted electron wave-function is a spherical wave centered on the source atom, with angular momentum components / 1, where / is the angular momentum of the core level. If the incident photon beam is polarized, the orientation of the emitted electron wave-function can be controlled. These electrons then propagate through the surface and are detected and analyzed as in LEED experiments. A synchrotron x-ray source normally produces the intense beams of variable energy polarized photons needed for photoelectron diffraction. 

Either a photon or an electron impinges on the surface. This photon or electron may be polarized to yield additional surface information. The electron, part of a well-collimated and monoenergetic electron beam, may be multiply scattered by surface atoms before reaching step 2. Multiple scattering is most marked at kinetic energies below about 200 eV and can make the process particularly sensitive to the surface structure at these lower energies. 

High-resolution electron HREELS surface. The channeling and blocking of scattered ions within the crystal can be used to triangulate deviations from the bulk structure. HEIS has been especially used to study surface reconstructions and the thermal vibrations of surface atoms. (See also MEIS and ISS.) A monoenergetic electron beam, usually 2 -10 eV, is scattered off a Molecular structure... 

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