The motion of energetic charged particles inside a monocrystalline solid can be strongly influenced by channeling and blocking effects. The present article reviews the theory, the experimental studies, and some of the applications of these effects. The coverage of the published literature extends through June 1973.

Channeling and related effects in the motion of charged particles through crystals

The morphology of porous anodic oxide films formed on aluminium in phosphoric acid electrolytes at constant current density or voltage, and under changing electrical or electrolytic conditions, has been studied quantitatively by electron microscopy. Replicas from film sections and from both film interfaces have been prepared, as well as transmission micrographs of thin films, produced under accurately defined conditions. During formation at constant current density, pore initiation occurs by the merging of locally thickening oxide regions, which seem related to the substructure of the substrate, and the consequent concentration of current into the residual thin areas. The pores grow in diameter and change in number until the steady-state morphology is established. The film barrier layer thickness has been measured directly for the first time. The steady-state barrier-layer thickness, cell diameter and pore diameter are all observed to be directly proportional to the formation voltage. It becomes evident that the barrier-layer thickness, decided largely by an equilibrium established between oxide formation in the barrier-layer and field-assisted dissolution (probably thermally enhanced) at the pore bases, determines the cell and pore sizes by a simple geometrical mechanism. Anion incorporation into the film and its hydrogen-bonded structure play secondary roles to these factors in determining the actual film morphology, although not its subsequent properties. A consequence of the mechanism is that, at constant current density, relatively non-aggressive electrolytes give thicker barrier layers, larger cells and larger pores next to the barrier layer than aggressive media, although subsequent pore widening at the outer surface of the film by simple chemical dissolution is more severe in aggressive electrolytes.

The morphology and mechanism of formation of porous anodic films on aluminium

Anodic Oxide Films

Porous anodic alumina: fabrication, characterization and applications

Energy levels of Z = 11−21 nuclei (IV)

http://www.nuclear.lu.se/fileadmin/nuclear/Undervisning/TillSubFys/PIXE-Amsel-microanalysis.pdf

G. Amsel

Papers

Microanalysis by the direct observation of nuclear reactions using a 2 MeV Van de Graaff

The mechanism of anodic oxidation

Microanalysis of Flourine by nuclear reactions

Microanalysis of Flourine by nuclear reactions: I. 19F(p, α0)16O and19F(p α γ)16O reactions

Depth profiling with narrow resonances of nuclear reactions: Theory and experimental use