摘要:

Comparing the experimental data with the known theoretical knowledge about interaction of irradiation with a substance one can conclude that the appearance of colour centres in the bulk of a LiF crystal is the result of a channelling motion of accelerated C+6ions, accompanied by the creation of neutrons due to the decay of lithium ions.

ISSN:0033-7579    

DOI:10.1080/00337578408215769

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Examination of the results of computer simulation of Cu single-crystal and polycrystal sputtering by 27 keV Ar ions started in Part I of the present work is continued. The spatial and energy distributions of all sputtered atoms and various sputtering components are analysed here. The incidence angles α = 45° and 85° are taken as examples. The sputtering is shown to be mainly near the <110> and <100> axes and also, especially in the case of glancing incidence, near a plane perpendicular to the ion beam. The mechanisms of predominant sputtering are discussed in detail. The importance of linear collision chains and correlated collisions of the incident ions with the atomic rows of a crystal lattice is emphasized. It is noted that bombardment of a crystal under semichannelling conditions is favourable for the target to be sputtered in the form of clusters. In connection with Harrison's recent remarks on Sigmund's sputtering theory, the relationship of the energy of sputtered atoms to the depth of their production in a crystal is examined. The mean depth from which the sputtered atoms are ejected has been found to be a nonmonotonic function of their energy.

ISSN:0033-7579    

DOI:10.1080/00337578408215770

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Spectral-angular characteristics of channeling radiation as a function of the initial beam energy are investigated by computer simulation of channeled particle trajectories. The above characteristics are shown to be essentially dependent on the correlation between the critical channeling angle and the characteristic radiation angle.

ISSN:0033-7579    

DOI:10.1080/00337578408215771

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Gamma-ray induced decomposition of the nitrate ion in solid solution of KBr crystal has been studied by infrared spectroscopy. The disappearance of the nitrate follows the rate law derived from the mechanism (1) NO3−→NO2− + O, (2) NO2− + O → NO3−, and (3) NO3− + 0 → NO2− + O2. At room temperatureki=l.3 ± 0.2 hr−1andk2/k3=70 ± l at a dose of 5.9 × 1019 eV hr−1g−1. The appearance of the nitrite ion follows the same rate law only at the initial stage of the reaction when its secondary destruction by the radiation is negligible. The nitrite ion itself decays by an apparent second order process but only about a third or less of its decomposition produces the nitrate ion.

ISSN:0033-7579    

DOI:10.1080/00337578408215772

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A simple expression for the screened Coulomb potential of ionized atom is derived from the Moliere approximation to the Thomas-Fermi potential of neutral atom on the basis of the energy minimization principle. This potential gives reasonable results in calculating minimum yields for planar channeling of protons in CaF2 and BaF2. The effect of ionic character of lattice atoms on the planar channeling is discussed.

ISSN:0033-7579    

DOI:10.1080/00337578408215773

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Experiments have been carried out to obtain the response curves (Vt/ Vgvs.Zeff2/β2) of Muscovite mica, Hostaphan, CR-39, phosphate glass, vitreous quartz glass, and soda-lime glass, dielectric track detectors. These detectors were exposed to different types of light and heavy charged particles. Differential etching of the latent damage trails was carried out, and (a)Vt, the etching velocity along the track, and (b)Vg, the general etching velocity, were measured at different stages of the etching process. Both optical and scanning electron microscopes (SEM) were employed in these studies. Among the detectors investigated here, CR-39 plastic has been found to be the most sensitive detector, while the sensitivity of soda-lime glass is the lowest.

ISSN:0033-7579    

DOI:10.1080/00337578408215774

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The fundamental processes and the mechanisms of low energy positron interaction with solid state surfaces are analyzed. The processes of positron retardation, inelastic scattering and inter-action with the particles and quasiparticles of the surface area of the solid state, and also the orocesses of the secondary particle excitation and positronium atom formation near the surface are considered and classified according to the energies. The theoretical concepts of elastic and nelastic scattering are developed; new experimental data are obtained on the backscattering of ow energy positrons for the diagnostics of the solid state surface properties.

ISSN:0033-7579    

DOI:10.1080/00337578408215775

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A study has been made of the influence of ion implantation of yttrium and dysprosium upon the thermal oxidation behaviour of two different stainless steels. The oxidation experiments were made in dry oxygen (1 atm pressure) at 876°C (Y+ implant) and at temperatures between 206 and 1093 °C (Dy+implant) for a period of 30 min. The oxidation behaviour and impurity distributions were studied using the l6O(d, p)017* nuclear reaction and Rutherford backscattering.

ISSN:0033-7579    

DOI:10.1080/00337578408215776

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The effects of low fluence (3 × 1015ions/cm2) Dy+implantation on the thermal oxidation of <110> Ni, Incoloy MA956 (Fe; 20% Cr; 4.5% Al; 0.5% Y2O3; 0.5% Ti) and an austenitic steel (Fe; 20% Cr; 25% Ni; 1.5% Ti) have been studied using RBS/channelling and the16O(d, p)17* nuclear reaction. The oxidation experiments were made in dry oxygen at 500°C for periods up to 2 hr.

ISSN:0033-7579    

DOI:10.1080/00337578408215777

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Comparative experiments on the formation and annealing of radiation defects in float-zonen-Si (ρ0≃200 ω cm) irradiated with 8600 MeV protons or 60Co γ-rays were carried out. From the analysis of the temperature dependences of the Hall coefficient the values of the activation energy δEof radiation defect ionization are determined. The annealing character and nature of radiation defects with close values of δEare found to be dependent on the kind of irradiation. The results obtained are discussed taking into account the radiation defect formation mechanism for the kinds of irradiation used and the influence of the potential barrier Ψ of proton-produced defect clusters on the value of δEfor defects localized in clusters (δE= δE— Ψ, where δEis the radiation defect ionization energy). Proton-irradiation-produced radiation defects with δE=Ec— 012 eV (annealing temperature range 200–300°C) are concluded to represent planar tetravacancies (Si-A3 centres) whose ionization energy is δE≃Ec— 0.23 eV, localized in the central region (the core) of the defect cluster.

ISSN:0033-7579    

DOI:10.1080/00337578408215778

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor