[en] Ion implantation in conjugated polymers can produce both doping (with suitable choice of ions) and damage in the form of broken covalent bonds. We consider the electronic and transport properties as assessed from measurements on poly(paraphenylene) of d.c. conductivity, thermopower and a.c. conductivity studied against temperature for various implantation parameters. Damage is produced at high implantation energies and high doses, and we find that transport phenomena occur mainly in degenerate states near the Fermi energy, exhibiting a p-type thermopower. We propose a model in which the sp² σ-dangling-bond states formed as a result of bond scission are filled from the π valence band. This partial emptying of the valence band is consistent with the transport properties. Lower implantation doses at lower energies induce doping in polaronic bands, with both p-type and n-type thermopower, depending on the ion implanted, although the effects of the defects present can appear, especially at low temperatures. (Author)

[en] Hydrogen transport through plasma-facing materials has been analysed. By comparing permeation fluxes limited to different regimes, six transport parameters are identified; these are coupled to distinguish the regimes of plasma-driven permeation of hydrogen in the steady state. Regime diagrams and subregime diagrams are obtained, 14 sets of regime diagrams being present in all. There are two RR areas, three RD areas, three DD areas and two DR areas in the subregime diagram (R indicating recombination, and D diffusion). The relative sizes of four permeation fluxes limited to different regimes are different in these areas. (author)

[en] The spin precession frequency ω_μ/2π of positive muons and the transverse μ⁺ spin relaxation rate Γ₂ have been measured on three Ni single crystals as a function of temperature and hydrostatic pressure between 7 and 660 K and up to pressures of 0.6 GPa. It is shown that above 260 K the Fermi contact field acting on the μ⁺ magnetic moments is proportional to the saturation magnetization, whereas at lower temperatures it is temperature independent apart from a small anomaly at about 8 K. The volume dependence B_Fermi does not exhibit any structure that might be attributed to the occupation of metastable sites by the μ⁺. The observed relaxation rates are compatible with the hypothesis that they are caused by internal strains associated with dislocations. (author)

[en] The tunnelling kinetics of muonium (Mu) atoms in solid nitrogen (s-¹⁴N₂) have been studied using the technique of Mu spin relaxation in weak longitudinal magnetic fields. At low temperatures the results are inconsistent with diffusion models using a single correlation time τ_c. Spatial inhomogeneity of solid nitrogen crystals arising at low temperatures results in a two-component behaviour of the muon polarization function. (author)

[en] The two paramagnetic muon states - normal and anomalous muonium -and the diamagnetic muon states have been investigated in different monocrystalline silicon samples (intrinsic, boron-, phosphorous-, or arsenic-doped, float-zone or Czochralski-grown) between 6K and 800K by means of longitudinal field-quenching (LFQ) and radio-frequency μ⁺ spin resonance (RFμSR). The LFO data can be described consistently by coupled equations of motion for the muonium spin systems if spin exchange processes as well as transitions between different muon states are taken into account. It is shown that the initial formation probabilities of the different muon states, the ionization rate of the anomalous muonium, and the electron spin exchange rates depend strongly on the charge carrier densities. These results are in agreement with the RFμSR data obtained on the same samples if the different time scales of RFμSR and LFQ experiments are taken into account. At temperatures above 300 K both RFμSR and longitudinal relaxation results appear to indicate reversible ionization of normal muonium. (author)

[en] The implantation of single-crystal CuInSe2 with O ions is known to cause an n- to p-type carrier conversion and a strong enhancement in photoconductive response. In this paper, we present the first microstructural investigation of O and Xe ion implant damage in CuInSe2 as a function of implant dose. Cross-sectional transmission electron microscopy and secondary-ion mass spectroscopy depth profiling have been used to characterize the implants. Our microstructural observations are correlated both with the theoretical implant profiles and with the measured photoconductivity of the material. (Author)

[en] Vacuum ultraviolet light from synchrotron and undulator radiation sources creates defects in hydrogenated amorphous silicon films. The dependence of the defect creation kinetics on photon energy has been investigated. The concentration of the defects induced by photons having an energy above 24 eV is proportional to the irradiation time. The rapid defect creation is due to the breaking of silicon-silicon bonds by the photo-induced plasmons. (author)

[en] Quasicrystalline Al-Cu-Co-Si was irradiated with 200 and 400 keV electrons approximately along the zone axes. Under these conditions the X-ray spectrum contains, apart from characteristic X-ray lines, additional peaks. From the dependence of the peak energies on the kinetic electron energy it is concluded that these lines stem from coherent bremsstrahlung. The ratio of some peak energies is very close to the golden mean τ=(5^1/2 + 1)/2. These measurements show that atoms in quasicrystalline Al-Cu-Co-Si are arranged in fairly well defined planes. It is confirmed for the first time that for the generation of coherent bremsstrahlung a periodic arrangement of atoms is not essential. (author)

[en] Theoretical estimates of the polishing of randomly rough surfaces by sputtering under uniform monodirectional ion bombardment are presented. The methods are based upon the Huygens wavefront construction and display the shrinkage of peaks and expansion of valleys. Peak shrinkage occurs rapidly and is less well predicted theoretically but valley expansion occurs over a longer time scale and is predictable from scaling laws developed for surface growth phenomena. The equivalent eroded depths required to reduce the roughness to specific levels are determined. (author)

[en] We present a detailed study of magnetization in UCu₂Ge₂, a system that undergoes a ferromagnetic to antiferromagnetic transition as a function of temperature. The nature of the ferromagnetic and antiferromagnetic states involved, and also of the phase transition, do not seem to be conventional. Marked irreversibility is observed in the low-temperature antiferromagnetic state in an external field up to 2 T, and distinct irreversibility exists even for the ferromagnetic state in the low-field regime (H ≤ 50 mT). (author)