摘要:

A polycrystal tungsten target (250°C) was bombarded with 150 keV ions of He, Ne, Ar, Kr, Xe, and Cu (current density 200 μA/cm2). With a mass and energy spectrometer the mass distribution of the sputtered charged particles was determined in the energy range 10 to 1250 eV. With increasing projectile mass the yield and the observable size of clusters Wn+increased. In the present study this yield decreased monotonously with increasingn. The maximum cluster size observed was W+12during sputtering with Xe+. The cluster yield decreased steeply with increasing cluster size and cluster energy. The slope of this energy dependence, however, appeared to be independent of the projectile mass. A crude kinetic model based on collision cascades is proposed to account for the cluster formation.

ISSN:0033-7579    

DOI:10.1080/00337577208231164

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The stopping powers of helium ions transmitted through silicon in channelling directions (<110> and <111> axes and {111} plane) and in random directions for the energy range from about 0.1 MeV to 18 MeV have been determined. For the channelled cases, stopping cross sections have been calculated using both the position of the leading edge and the peak of the channelled energy spectra. Evidence is presented to support the view that the leading edge of the energy spectrum corresponds to the energy loss of the best channelled particles. It was found that the ratio of the channelled-to-random stopping, using either of the above-mentioned channelled stopping powers, is a function of the helium-ion energy havinga maximum value at the same energy at which the maximum in the stopping cross section is observed. For <110> channelling, this ratio for the best channelled ions varied from about 0.3 at 0.1 MeV to a maximum of about 0.55 and decreased to a limit of about 0.3 at high energies. The relation between the values of stopping powers determined in our transmission experiments and those applicable to depth calculations in Rutherford-scattering experiments is discussed.

ISSN:0033-7579    

DOI:10.1080/00337577208231165

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The dechanneling of 150 keV protons impinging along the <110> direction in nearly perfect copper crystals has been investigated by measurements of the 135° backscattered protons and of the yields of the characteristic Cu(L) X-rays, as a function of the crystal temperature (300 °K, 485 °K, and 645 °K) and the incident beam direction relative to the <110> channel. The data are analyzed and interpreted in a two step procedure. First, the data are reduced in terms of the energies of the observed backscattered protons taking into account the contributions of dechanneled protons and of the protons knocked onto random trajectories by the surface atoms. Second, model backscattering spectra and X-ray yields are constructed by assuming various trial functions for the dependence of the dechanneling rate, on penetration depth. Two trial functions are tested. One is based on a small-angle multiplescattering model of dechanneling. The other assumes an exponential decay of the number of channeled protons, characterized by a mean free path until dechanneling. The data support the latter. The shortening of the mean free path with rising crystal temperature suggests that scattering on the thermally displaced lattice atoms is the primary cause for dechanneling.

ISSN:0033-7579    

DOI:10.1080/00337577208231166

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Random numbers are used to describe the plural scattering of fast heavy ions by amorphous metal films. Rather simple expressions for the single interactions are derived employing a screened Coulomb potential and with regard to the important energy losses of the particles in the foils. As a first result the computer program yields qualitatively the shape of the particle trajectories in accordance with observed fission fragment tracks in thin metal films. Furthermore the spatial distribution of the reflected particles together with the total reflection rate is studied as a function of the entrance angle. It is seen that the portion of the reflected particles decreases rapidly with increasing angle. Similarly the penetration depths and the energy spectra are strongly influenced by the angle of the incident beam. The results are in satisfactory agreement with known experiments.

ISSN:0033-7579    

DOI:10.1080/00337577208231167

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The energy losses of light ions channeled through Si were investigated by studying the energy distribution of the transmitted particles. Beams of protons, deuterons and helium ions have been used in the energy range from 0.9 to 5.0 MeV.

ISSN:0033-7579    

DOI:10.1080/00337577208231168

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The energy spectra of atoms sputtered from a gold target have been measured as a function of ion energy and species for target temperatures in the range 100 to 1200°K. Both single crystal and polycrystal targets have been used, with surface topography monitored by a scanning electron microscope.

ISSN:0033-7579    

DOI:10.1080/00337577208231169

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The energy and angular dependences of the energy distributions of 10–30 keV helium ions scattered by solid targets have been studied. It was found that when the primary helium ion energy is high enough the energy distributions of the scattered ions are broad and cupola-shaped. At the high-energy edge of the distributions a narrow single peak was observed. It was found that the half-widths of the energy distributions depend strongly upon both sliding and scattering angles, upon the atomic number of the target substance, and upon the energy of the primary ions.

ISSN:0033-7579    

DOI:10.1080/00337577208231170

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

PRODUCTION ET RESTAURATION DES DEFAUTS PRODUITS PAR DES ELECTRONS A BASSE TEMPERATURE DANS LE CADMIUM On a irradié du cadmium par des électrons de 3 MeV à 20°K et étudié la restauration des défauts cristallins par des mesures de résistivité électrique. On compare nos résultats à ceux obtenus auparavant par R. R. Coltman concernant du cadmium irradié par des neutrons thermiques. Les différentes hypothèses pour expliquer ľimportant stade III sont discutées à la lumière des résultats connus sur les défauts ďirradiation et les défauts de trempe dans le cadmium.

ISSN:0033-7579    

DOI:10.1080/00337577208231171

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor