ISSN:0033-7579    

DOI:10.1080/00337577208231154

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Experiments have been undertaken to determine the feasibility of finding the location of the atoms of a pseudomorphic monatomic layer of silver on a palladium substrate. 200 keV He++ions are scattered off the palladium substrate before and after coating with an epitaxial silver film, the direction of incidence being along the <100> and <110> crystal directions, so that the backscattered yield is reduced by channeling of the He ions. Silver atoms that are aligned with atomic rows along the direction of incidence do not increase the yield of ions backscattered off the surface, whereas atoms that are interstitial to the atomic rows of the substrate do increase the vield. It is concluded that the technique is useful, particularly as an adjunct to LEED and Auger spectroscopy, in the study of film structure.

ISSN:0033-7579    

DOI:10.1080/00337577208231155

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The Focker-Planck equation for scattering of channeled ions by electrons and thermal vibrations of crystalline lattice atoms has been obtained and solved. For calculations use is made of two models of the electron density distribution in a channel: the Thomas-Fermi model and the free-electron model. Axial and planar channeling is considered.

ISSN:0033-7579    

DOI:10.1080/00337577208231156

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The variation of shape of angular dips with penetration depth has been investigated by the backscattering technique for 0.3 to 1.5 MeV protons and deuterons impinging on Si and Ge single crystals at different temperatures.

ISSN:0033-7579    

DOI:10.1080/00337577208231157

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Minimum yield of backscattered protons and H-atoms with primary energies of 50–150 keV from a well annealed Nb single crystal has been measured in single and double alignment as a function of emerging energy at different temperatures. From these data minimum yield as a function of depth has been calculated, assuming electronic energy losses only. The results are compared to analytical equations for minimum yield in single and double alignment. These equations were obtained from Lindhard's theory of electronic and nuclear multiple scattering in single crystals. It was assumed that transverse energy increases steadily with penetration depth, diffusion being neglibible. At higher energies the agreement between theory and experiment is good in <100> single alignment. In <110> single alignment and at lower energies experimental values are about a factor of 2 higher. In double alignment there is a discrepancy of nearly one order of magnitude, which probably must be attributed to lattice defects.

ISSN:0033-7579    

DOI:10.1080/00337577208231158

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The temperature dependence of minimum yield and dechanneling coefficient is studied for <110> and <111> axial channeling in germanium and silicon crystals. The observed minimum yield and the dechanneling coefficient are represented by linear relations of the mean square amplitude of thermal vibrations, and the results are compared with theory. For the minimum yield, the observed values are independent of energy and kind of particles and agree with theoretical values. The dechanneling coefficients show a poor agreement with theory. To find a reason for this discrepancy, the critical angle and the theoretical treatment are considered and discussed.

ISSN:0033-7579    

DOI:10.1080/00337577208231159

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Results are presented on the Rutherford scattering yield of 1 MeV protons in a 500 Å thick gold crystal. Experimental results obtained for planar channeling are in good agreement with the theoretical values of the depthXm, and the half-width ψ1/2that we have got from a calculation in which the effects of the thermal motion of lattice atoms and the effects of nuclear multiple scattering on the scattering yield are taken into account.

ISSN:0033-7579    

DOI:10.1080/00337577208231160

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The general features of dechanneling by lattice defects are briefly described. The dechanneling cross section of a defectAand the opacity of a crystal ω Rare defined. Stacking faults and dislocations are more specifically studied in the case of planar channeling.

ISSN:0033-7579    

DOI:10.1080/00337577208231161

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The sputtering yield of copper has been measured with 21 different 45-keV ions as projectiles. The measurements were performed by means of an oscillating quartz micro-balance. This allows the sputtering yield to be accurately measured even if only 40–50 Å of the target material was sputtered away. It was found that the measured sputtering yield depended sensitively on the previous irradiation of the target. We therefore preferred to measure all sputtering yields relative to copper self-sputtering. This ratio of sputtering yields was found to be insensitive to previous bombardments and to agree well with Sigmund's theory, although small systematic disagreements are found. The overall agreement implies firstly that the modifications of the target during bombardment only affect the ejection conditions at the surface, and secondly that any Z1oscillations of the nuclear stopping power are less than 10 per cent.

ISSN:0033-7579    

DOI:10.1080/00337577208231162

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The sputtering of single crystals of radioactive gold by well collimated beams of energetic ions has been investigated in detail, using cylindrical collectors. For 80 keV argon ions incident in and near to <100> channels there is a very sensitive dependence of the height and shape of the <110> spots on angular deviation. This is shown to be a consequence not only of the size and degree of order within anatomic cascade, but also ofits positionbelow the bombarded surface, following ion dechannelling. At angles of incidence such that cascades lie at very shallow depths the <110> spots develop an internal structure, which is shown not to be an artefact, but can be due to not fully focused collision sequences, from the cascade.

ISSN:0033-7579    

DOI:10.1080/00337577208231163

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor