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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 18 (1979), S. 391-398 
    ISSN: 1432-0630
    Keywords: 61.80 ; 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The computer simulation program MARLOWE which follows the trajectories of energetic ions and recoiling target atoms in solids has been used to calculate sputtering yields for low energy (0.1–10keV) light ions (H, D, T,4He). Recoil energy densities were calculated for comparison with analytical theories. The sputtering yields obtained for amorphous Fe agree within a factor of two with experimentally measured values for polycrystalline stainless steel, while the calculated yields for protons on amorphous molybdenum are more than twice the experimental values on polycrystalline material. The calculations show that in the parameter range investigated, ions backscattered in the solid contribute a major part to sputtering. This result confirms earlier calculations of the threshold energy for sputtering which are in agreement with recent measurements.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 31 (1983), S. 37-44 
    ISSN: 1432-0630
    Keywords: 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The areal density and the depth distribution of3He trapped in Ni as a function of the bombarding fiuence was measured in the energy range of 1–25 keV and at angles of incidence between 0 and 85° using nuclear reaction analysis. At fluences below saturation a linear relation is found between the areal density and the fiuence. From its slope the trapping and reflection coefficients can be determined. The experimental data for trapping and reflection coefficients and for the depth profiles were compared with computer simulation results from the TRIM program. To reduce uncertainties in the absolute values of the experimental trapping coefficients, they were normalized to the TRIM values at normal incidence. The dependence of the measured reflection coefficient on the angle of incidence between 0 and 80° shows good agreement with the calculated data for incident energies from 3 to 25 keV, but for 1 keV the measured reflection coefficients are higher than the calculated ones.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3833-3837 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Soft carbonized layers prepared in a glow discharge, with a hydrogen concentration of H:C∼4/3, are exposed to helium ion bombardment at energies between 0.3 and 2.6 MeV. A strong ion-induced depletion of up to 3×103 H atoms per incident 4He+ ion is observed by means of high-energy ion beam analysis. The hydrogen release is shown to be a local process, with the electronic energy deposition as the main responsible mechanism. The results are successfully compared to a model which takes into account local bond breaking and retrapping and the local formation of hydrogen molecules.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2225-2233 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work the buildup of damage due to deuterium implantation in highly-oriented pyrolytic graphite (HOPG) is investigated. HOPG was implanted with 10–30 keV D3+ at different target temperatures between room temperature and 773 K with fluences from 1014 to 1018 D/cm2. Subsequently, the damage due to the implantation and the retained deuterium were measured by Rutherford backscattering (RBS) in a channeling direction (RBSc) and by the D(3He, p)α nuclear reaction analysis (NRA), respectively. The damage of selected samples was additionally observed with transmission electron microscopy (TEM). The initial trapping efficiency is unity in the whole temperature and energy range. The maximum retention of the deuterium, however, depends on the temperature and implantation energy. The damage in HOPG measured with RBSc starts to saturate at 5×1015 D/cm2 (295 K) and 1.3×1017 D/cm2 (773 K). Both fluences are well below the fluence at which amorphization is observed in TEM.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6609-6615 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The particle reflection coefficient is determined experimentally and by computer simulation for the bombardment of two different kinds of carbon with deuterium at normal and oblique incidence in the energy range from 1 keV down to 33 eV. Highly oriented pyrolytic graphite (HOPG) and EK98 graphites served as targets, the former as an example with a relatively flat surface, the latter with a rough surface topography. The experimental technique is based on the measurement of the trapped amount by nuclear reaction analysis using the reaction d(3He,p)α; protons are detected with a surface barrier detector. It is found that the usual assumption of complete trapping at low fluences is not fulfilled at low energies (≤100 eV). This is demonstrated by measuring the decrease of the implanted amount of deuterium with further bombardment of protons at the same energy. This loss of implanted atoms can be described by an exponential function which can be used to determine the correct trapping coefficient and from this the correct particle reflection coefficient. The experimentally determined particle reflection coefficients for HOPG agree reasonably well with data calculated with the Monte Carlo program TRIM.SP (version TRVMC); only at the lowest energy of 50 eV the experimental values are somewhat higher at intermediate angles of incidence than the calculated ones. The rough surface of EK98 is investigated with a scanning tunneling microscope. It is found that this surface can be described by a fractal surface of dimension 2.05. For this surface agreement of the experimental values with those calculated with the program VFTRIM (based on TRIM.SP, assuming a fractal surface) is found. © 1995 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 137-148 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Helium reemission, trapping, and thermal desorption from highly ordered pyrolytic graphite (HOPG and HPG) of different orientation, polycrystalline graphite (EK98), and titanium doped graphite (RG-Ti-91) have been measured at irradiation temperatures of 300 K and 800 K. The implantation was performed with a 40 keV 4He ion beam. Detailed transmission electron microscopy (TEM) investigation of the microstructure evolution was made on the implanted specimens. He reemission from basal oriented (BO) highly oriented pyrolytic graphite is accompanied by blistering and flaking leading to repetitive gas bursts. On edge oriented (EO) pyrolytic graphite three reemission peaks are observed during room temperature implantation, the first and smallest one being assigned to He release from intrinsic lenticular cavities, the second one occurs during early bubble formation when a small amount of implanted gas still escapes accumulation, and the third and largest peak being due to He release by bubble coalescence. The He reemission rate grows very slowly at room temperature and does not reach 100% up to the highest implanted fluence of 3.5⋅1018 He/cm2. At 800 K the He reemission rate from EO pyrolytic graphite reaches 100% immediately after starting implantation due to the high diffusive mobility of He.EK98 and RG-Ti-91 show similar reemission behaviour. No gas bursts due to blistering are observed. The initial reemission rate at 300 K is higher than in EO pyrolytic graphite due to release of He via a network of intergranular channels. At 800 K reemission is rather similar to that from EO pyrolytic graphite. No thermal desorption of He from BO HOPG up to 1200 K is observed for implanted fluences ≤1016 He/cm2. At higher fluences the onset temperature of desorption decreases from 750 K at 2⋅1016 He/cm2 to 380 K at 1017 He/cm2 caused by thermal flaking due to pressure increase of He in submicroscopic cracks. In the other materials two desorption peaks are observed, the first one being related to He release from "solid solution,'' while the second is attributed to gas escape from He filled bubbles. In contrast to the conclusions of Niwase et al. we find from the reemission kinetics and from selected area electron diffraction patterns (SADP) that graphite implanted at 300 K with He up to a damage of 10 dpa and more cannot be regarded as amorphous and shows a distorted turbostratic structure. The c parameter increases to (3.6..3.7)A(ring). Radiation effects in graphite implanted at 800 K are less pronounced up to damage levels of 200 dpa but may decrease the He diffusion coefficient. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3169-3177 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of the retention of deuterium in polycrystalline nickel were obtained at 193 and 223 K through elastic-recoil detection using a 2.6-MeV 4He beam. The depth profiles so obtained show striking differences with their counterparts measured at higher temperatures. Although the profiles are homogeneous at implanted fluences lower than 3×1018 D+ cm−2, they present a large peak centered slightly deeper than the implantation range at higher fluences. Additional features develop as one further implants. The large peak is associated with the buildup of nickel deuteride. A one-dimensional computer model is developed which partly reproduces the features of the measured depth profiles.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1893-1897 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Depth profiles of 10-keV deuterium implanted in nickel were obtained during implantation through elastic recoil detection between 233 and 313 K. The profiles were allowed to reach saturation at each measured temperature. At the lowest temperature, measurements with various implantation fluxes were performed. Aside from surface peaks, the depth profiles show a uniform density of deuterium in the implanted layer and the shape of these profiles is independent of the sample temperature or implantation fluence or flux. The temperature and fluence dependence could be successfully reproduced with a trapping-detrapping model considering three different trap binding energies. Two of the model parameters are in good agreement with previous calculations performed to reproduce reemission measurements.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 163-168 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hard amorphous films of a-C:H and a-C:D were deposited by a rf glow discharge in either CH4 or CD4 . By ion bombardment with protons and deuterons, the H/D exchange process was studied as function of the bombardment fluence by means of depth profile measurements. The local hydrogen and deuterium contents are not adding up to a constant "saturation'' value: the local mixing model is not valid. Instead of that an initial depletion appears, which depends on the incident energy of the ions. At higher fluences, the total (H+D):C ratio tends to increase again, due to an increasing influence of the deposition process. This demonstrates a structural difference between a-C:H films and hydrogen-saturated layers of implanted carbon.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2068-2072 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hard amorphous films of a-C:D were deposited by a rf glow discharge in CD4. The implantation of 40-keV 3He+ ions in these films was studied as a function of the helium fluence at temperatures between 100 K and room temperature. The trapped amounts of helium and the deuterium losses in the layer were measured in situ using nuclear reaction analysis with 0.5-MeV D+ and 1-MeV 3He+ beams, respectively, and subsequent ex-situ elastic-recoil detection analysis. A transient helium retention appears in the carbonized layers, occurring only at temperatures below 200 K. Above a critical fluence which depends on temperature and ion flux, outdiffusion of He is observed which is ascribed to the formation of diffusion channels by radiation damage. The deuterium depletion induced by helium bombardment below 200 K sets on in correlation with the helium outdiffusion, but is otherwise independent of the helium trapping.
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