摘要:

A quantum theory of electromagnetic radiation of relativistic particles has been developed with allowance for channelling and thermal vibrations of crystal nuclei. A general formula for the probability of radiation has been derived after averaging over initial and summing over final polarizations of a particle and polarization of photons. Averaging over crystal states of nuclei has been made in both cases: with excitation of phonons and without it. The total radiation has been shown to be formed by channelled and Bremsstrahlung radiations in interrelated way. It has been established that incoherent Bremsstrahlung arises in scattering on thermal vibrations. The particular conditions determining the properties of this radiation in channelling have been derived from the general formula and analyzed.

ISSN:1042-0150    

DOI:10.1080/10420159008220549

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A pseudo-potential technique has been applied to calculate the annihilation rates for positrons in bubbles of helium gas in gold and silver. The positron pseudo-wavefunction in each case was found to be in a surface state of the metal, the exact form of which displayed a slight dependance on the density of the helium gas. The annihilation rate of the positron was the sum of a nearly constant surface rate and a strongly density dependant annihilation rate with the helium electrons. There is a trend for annihilation with the helium to be greater in metals with low free electron densities, the helium in such metals resting closer to the metal surface thus increasing the overlap of the positron wavefunction with the helium.

ISSN:1042-0150    

DOI:10.1080/10420159008220550

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Electron diffraction studies have been made of polycrystalline Ni films irradiated with well separated beams of ions of different nature, namely ions of inert (He+, Ne+, Ar+, Kr+, Xe+) and reactive (N+and O+) gases. The Ni films were prepared under vacuum conditions (P≳ 3·10−6Pa during evaporation) preventing an appreciable contamination of the films with impurities. The samples were irradiated atT≈ 300 K with ion beams of energies from 10 to 100 keV in the dose range between 5·1016cm−2and the value leading to sample destruction.

ISSN:1042-0150    

DOI:10.1080/10420159008220551

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A model for the impurity redistribution in heavily doped silicon layers suggested by Mathiot and Pfister6is modified. Two channels of impurity diffusion are taken into account: a redistribution of impurity inside of a percolation cluster and a standard diffusion outside of that cluster. The parameters of the model are identified for the case of rapid thermal annealing of antimony in silicon. The modified model better describes the observed diffusivity dependences on temperature and doping level.

ISSN:1042-0150    

DOI:10.1080/10420159008220552

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Kinetics of post recoil isothermal annealing of crystalline Ba/CoEDTA/2irradiated in a nuclear reactor or doped by60Co(II) reveals a combination of a monotonous and an oscillatory part amounting 1-3% of the total. The permanent recombination has been found to consist of two first order processes leading to the octahedral structure of the six-co-ordinated60Co(III).

ISSN:1042-0150    

DOI:10.1080/10420159008220553

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Decomposition reactions of NaClO3, KClO3, and KIO4induced by 3 keV Ar+ions and 1254 eV X-rays are investigated by X-ray photoelectron spectroscopy (XPS). The reactions lead to the formation of binary halides with preferential losses of oxygen. The decomposition pattern, monitored at the various stages of reaction, indicates almost direct changeover to the final products with only a few intermediate species formed. Product abundancies are compared for the ion, X-ray, and electron induced reactions and discussed in relation to the various radiation induced reaction mechanisms.

ISSN:1042-0150    

DOI:10.1080/10420159008220554

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Luminescence signals produced during ion implantation of sapphire are related to the F, F+and F2defect centres. However, the efficiency of light production changes with ion beam dose, the rate of energy deposition and radiation damage, hence the signals are not proportional to the defect concentrations. Data are presented which suggest that the light is primarily produced by electronic excitation. Luminescence efficiency within the region of nuclear collisions is very low. It is not possible to determine the energy dependence of the luminescence intensity, as a function of ion energy, by energy variations within a single target crystal.

ISSN:1042-0150    

DOI:10.1080/10420159008220555

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A semi-empirical model, based on concepts used to explain the process of track formation in insulators, has been applied to the experimental observation of improved film adhesion produced by MeV ion irradiation. Good agreement is obtained with experimental data for the system of gold film on native oxides of tantalum. The model uses a single free parameter,e0, which represents the threshold energy density for the process responsible for the improved bonding. The significance of this parameter is discussed in terms of possible ionisation induced interface phenomena.

ISSN:1042-0150    

DOI:10.1080/10420159008220556

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We have studied the effects of 2.5 MeV electron irradiation and ion (C, N, F, Si and Kr) bombardment on the electrical conductivity of a polyimide (Kapton-H) with ion energies ranging between 320 keV (N) and 1.25 GeV (Kr). In this wide range of situations we have tried to sort out the respective effects of nuclear and electronic excitation energy losses.

ISSN:1042-0150    

DOI:10.1080/10420159008220557

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Boron was implanted into several solids in the dose regime 1014to 1016ions/cm2and at energies between some 10 keV and some MeV. Measurements of the corresponding depth distributions were performed by means of the10B(n, α0)7Li(gnd) and10B(n, α1)7Li*(1st) nuclear reaction techniques with thermal neutrons, and by SIMS. The results are compared to theoretical predictions.

ISSN:1042-0150    

DOI:10.1080/10420159008220558

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor