Molecular beam epitaxy

LEED and Auger electron observations of the SiC(0001) surface

Field Emission Energy Distribution (FEED)

The exponential increase in computational processor speed, the development of novel computational architectures, together with the tremendous advances in ab initio theoretical methods that have emerged over the past two decades have led to unprecedented advances in our ability to probe the fundamental chemistry that occurs on complex catalytic surfaces. In particular, advances in density functional theory (DFT) have made it possible to elucidate the elementary steps and mechanisms in surface-catalyzed processes that would be difficult to explore experimentally. The advanced state of plane wave DFT has made it possible to rapidly examine systematic changes to the metal or the reactant in order to establish structure-property relationships. As a result, extensive data based on the energetics for various different surface-catalyzed reactions has been generated. This invites a detailed theoretical analysis of the factors that control reaction paths and corresponding potentialenergy surfaces of surface reactions. Such a theoretical analysis will not only provide interesting new insights into the intricate relationship between the chemical bonding features, structure, and energies of transition states but also serve as a basis for the development of analytical expressions that relate transitionstate properties to more easily accessible thermodynamic properties. The Brønsted-Evans-Polanyi (BEP) relationship is one such example which has been widely applied in the analysis of surface elementary reaction steps.1-8 δEact )RδEr (1)

Reactivity Theory of Transition-Metal Surfaces: A Brønsted−Evans−Polanyi Linear Activation Energy−Free-Energy Analysis

Recent advances in epitaxy

A LEED study of the epitaxial growth of copper on the (110) surface of tungsten

A low energy electron diffraction study of the structural effect of oxygen on the (111) face of a tungsten crystal

Thin reaction layers and the surface structure of silicon (111)

A magnetic lens for imaging and rotation of a charged particle beam includes a pair of focus elements axially spaced along a lens bore through which the beam passes and a rotation element positioned axially between the focus elements. Each of the lens elements includes a polepiece having opposing portions surrounding the lens bore and axially spaced apart to define a circumferential gap, and a winding for energizing the polepiece and the gap. The focus elements are energized by equal and opposite magnetic fields which focus the electron beam without substantial beam rotation. The beam can be rotated, without substantial change in focus or magnification, by varying the magnetic field of the rotation element. The lens is particularly suited for use in a shaped electron beam lithography system.

Multi-gap magnetic imaging lens for charged particle beams

A retarded field electron diffraction spectrometer is disclosed which includes an electron gun for directing substantially monoenergetic electrons onto the surface to be examined of a target to produce scattered electrons from such surface. A spherical retarding grid structure is concentrically disposed of the target in the space between the target electrode and a concentric spherical fluorescent screen. A retarding potential applied to the retarding grid permits only those target scattered electrons having a potential greater than the potential of the retarding electrode to reach the fluorescent screen. The retarding grid electrode has grid openings defining electron passageways having a characteristic diameter less than three times the characteristic length thereof to improve the uniformity of the retarding field. A spherical shield grid electrode is concentrically disposed of and has a radius within the range of 0.3 to 0.8 of that of the retarding grid to enhance the resolution of the spectrometer.

Norman J Taylor

Papers

A LEED study of the epitaxial growth of copper on the (110) surface of tungsten

A low energy electron diffraction study of the structural effect of oxygen on the (111) face of a tungsten crystal

Thin reaction layers and the surface structure of silicon (111)

Multi-gap magnetic imaging lens for charged particle beams

Retarding field electron diffraction spectrometer having improved resolution