Face Of Copper Crystal Research Articles

Directional effects of the molecular ion reflection from a crystal surface

The reflection of 30 keV molecular N + 2 ions from the (100) face of copper crystal has been studied experimentally. Under the examined experimental conditions, the yield of the reflected molecular ions has been found to sharply increase when the primary ion incidence plane gets parallel to the axis of the surface semichannels formed by the close-packed atomic rows of a single-crystal target. The magnitude of the effect is more than 15 times as high compared with random orientation of the primary beam with respect to the irradiated crystal target.

Directional effects of the molecular ion reflection from a crystal surface

The reflection of 30 keV molecular N + 2 ions from the (100) face of copper crystal has been studied experimentally. Under the examined experimental conditions, the yield of the reflected molecular ions has been found to sharply increase when the primary ion incidence plane gets parallel to the axis of the surface semichannels formed by the close-packed atomic rows of a single-crystal target. The magnitude of the effect is more than 15 times as high compared with random orientation of the primary beam with respect to the irradiated crystal target.

Focusing of ions scattered by crystals

Angular and energy distributions of 30-keV energy argon ions scattered by (100) face of copper crystal were experimentally studied. It was found that the half-widths of the angular distributions vs azimuthal angle of target rotation exhibit dips at aligned orientations of the target relative to primary ions.

Angular distributions of H 2 desorbed from the (100), (110), and (111) faces of copper crystals

The angular distributions of hydrogen molecules desorbed from copper have been measured for single-crystal surfaces of three different orientations: (100), (110), and (111). The surfaces were cleaned to the degree that the impurities were below the level of detection by Auger electron spectroscopy. The angular distributions were all significantly more peaked at the surface normal than the distribution corresponding to diffuse emission, i.e., where the molecular flux is proportional to cos θ, where θ is the angle measured from the surface normal. We have characterized the observed angular distributions by fitting the emperical expression cos d θ to the data, where d is an adjustable parameter. The results are: d ≈ 5 for (100); d ≈ 2.5 for (110); d ≈ 6 for (111). The distributions are nearly symmetric about the azimuthal angle between the plane of detection and the principal axes of the surface lattice. Possible models are considered.

Etch Pits at Dislocations in Copper

A modification of an etch discovered by Lovell and Wernick has been shown to be a reliable means of revealing dislocations as etch pits on (111) faces of copper crystals. The etch has been employed to study dislocation distributions in as-grown, annealed, and deformed crystals. A high-temperature anneal is found to lower the dislocation density of melt-grown crystals. A ``double-etch'' technique is employed to observe the motion of dislocations, and to show that the dislocations initially present in these crystals are mobile at low stresses. Subboundaries are numerous in these crystals and are found capable of hindering dislocation movement. Observations of the dislocation structure of crystals deformed in bending and in tension are reported, including the appearance of ``glide polygonization'' after room-temperature deformation.