Elastic Recoil Detection Analysis

We have built a novel apparatus for the investigation of materials for the storage of ultracold neutrons. Neutrons are filled into a storage volume, confined at the bottom by a magnetic field, at the top by gravity and at the sides by the slitless sample surface under investigation. For different beryllium and diamond-like carbon samples, storage times up to 200 s were obtained at room temperature. The corresponding loss parameters Z for ultracold neutrons varied between 4.2 and 6:8 Â 10 À4 per wall collision.

We studied the rearran gement of ion-implanted hydrogen in <100 > oriented n-type silicon wafers upon annealing and its effect on the crystal damage . The silicon samples were implanted with 42 keV protons to a dose of 2 x 1016 H /cm2 and subsequently vacuum annealed at temperatures r anging from 200 °C to 500 °C . The evolution of the H-concentration and the crystal damage depth profiles during the heat treatments were investigated through the combined use of elastic recoil detection (ERD) analysis, secondary ion mass spectroscopy (SIMS), and Rutherford backscattering spectroscopy (RBS) in channeling mode . The obtained results reveal information about the damage accumulation caused by the thermally induced rearrangement o f

Ion scattering experiments have been performed with a 3-30 MeV AVF cyclotron. The wide range of available energies combined with proper beam handling allows many scattering techniques to perform. At first an example of ordinary Rutherford backscattering spectrometry will be demonstrated on model catalysts as studied in surface chemistry. High energy backscattering spectrometIy with 8.8 MeV He ions, which enhances the sensitivity for oxygen, has been applied to study the oxygen removal from corroded archaeological artefacts upon treatment with a H, plasma. Elastic recoil detection analysis will be shown feasible with He ions having incident energies between 10 and 15 MeV once combined with a thin film detector. The development of a setup for ion channeling experiments with the cyclotron is reported and first results promise to increase the angular resolution in lattice deformation studies.

The storage of ultracold neutrons (UCN) in a combined magnetic, gravitational, and material trap is described. Wall materials investigated were diamondlike carbon (DLC) coatings on solid and flexible foil substrates as well as beryllium coatings on solid substrates. The loss coefficient per wall collision, η, and the depolarization probability β were measured simultaneously as a function of temperature (from 70 to 400 K) and energy (from 30 to 80 neV). The results at 70 K are η = (0.7 ± 0.1) × 10 -4 , β = (15.4 ± 1.0) × 10 -6 for DLC on polyethyleneterephtalate (PET) foil and η = (1.7 ± 0.1) × 10 -4 , β = (0.7 ± 0.3) × 10 -6 for DLC on aluminum foil. At room temperature the loss coefficients are larger by a factor of about 2 whereas the depolarization probabilities are found to be independent of temperature. The corresponding values for Be at room temperature are η ∼ 5 × 10 -4 , β ∼ 10 × 10 -6 . The DLC results for β and for the temperature-dependent part of the loss coefficient, η T , are interpreted in terms of incoherent scattering by hydrogen. The hydrogen admixture was measured independently by elastic recoil detection analysis to be about 1 × 10 16 atoms/cm 2 . The data do not support the hypothesis of hydrogen being chemically bound within the top layers of the DLC. Using two different models with a thin waterlike film on top of the substrate we obtain consistency between the temperature-dependent loss contribution and the measured hydrogen contamination.

Nickel-alumina/silica thin film materials for the use in solar thermal absorbers have been investigated using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Elastic Recoil Detection Analysis (ERDA). The TEM images revealed that all layers have a very small thickness variation and that the layers are completely homogenous. High resolution images showed 5-10 nm (poly) crystalline nickel nanoparticles. ERDA showed that both the silica and alumina compositions contain more oxygen than 2:1 and 3:2 respectively. SEM showed the surface morphology and characteristics of the top silica anti-reflection layer. Hybrid-silica has showed to generate a smoother surface with less cracking compared to pure silica. The final curing temperature revealed to be of importance for the formation of cracks and the surface morphology.

Amorphous (a) and nanocomposite Ti-Si-C coatings were deposited at rates up to 16 µm/h by direct current magnetron sputtering from a Ti 3 SiC 2 compound target, using an industrial pilot-plant system, onto high-speed steel, Si, and SiO 2 substrates as well as Niplated Cu cylinders, kept at a temperature of 200 or 270 °C. Electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction analyses showed that TiC/a-C/a-SiC nanocomposites were formed consisting of textured TiC nanocrystallites (nc) embedded in a matrix of a-C and a-SiC. Elastic recoil detection analysis showed that coatings deposited at a target-to-substrate distance of 2 cm and an Ar pressure of 10 mTorr have a composition close to that of the Ti 3 SiC 2 compound target, as explained by ballistic

Common conductive inks can be classified into three categories, which are noble metals, conductive polymers and carbon nanomaterials. Carbon nanomaterials offer many potential opportunities to be applied in printed and flexible electronics. Therefore, this paper aims to produce highly functional conductive ink using graphene nanoparticles with epoxy as a binder. As a baseline, graphene-filler conductive ink was formulated using a minimum percentage at the beginning. Then, the filler loading was increased based on the required conductivity level. This is to make sure the materials are in contact with each other and the movement of an electron will become easier. The formulation of ink, mixing process, printing process and curing process were performed to produce highly conductive graphene ink. The electrical and mechanical properties were assessed using a Four-point probe as per ASTM F390 and Dynamic Ultra Micro Hardness (DUMH) test as per ASTM E2546-1. Graphene Nanoplatelet (GNP) ag...

KeV ion irradiation of frozen benzene layers (-1 pm thick) gives rise to carbonaceous materials. The evolution of atomic structure of benzene leading to the arrangement of graphitic cluster inside the so called "Ion Produced Hydrogenated Amorphous Carbon" films (IPHAC) is discussed. UV-visible, infrared spectroscopy and Elastic Recoil Detection Analysis (ERDA) are used to distinguish the aliphatic and aromatic contribution in the amorphous structure. Application of these results to astrophysics lies in the possibility to explain the observed extended red emission and near-infrared continuum emission in several astronomical objects. Ion irradiation appears also to be able in producing, starting from simple hydrocarbon, compact polycyclic aromatic hydrocarbon molecules presently believed to be abundant constituents in our as well as in other Galaxies.

KeV ion irradiation of frozen benzene layers (-1 pm thick) gives rise to carbonaceous materials. The evolution of atomic structure of benzene leading to the arrangement of graphitic cluster inside the so called "Ion Produced Hydrogenated Amorphous Carbon" films (IPHAC) is discussed. UV-visible, infrared spectroscopy and Elastic Recoil Detection Analysis (ERDA) are used to distinguish the aliphatic and aromatic contribution in the amorphous structure. Application of these results to astrophysics lies in the possibility to explain the observed extended red emission and near-infrared continuum emission in several astronomical objects. Ion irradiation appears also to be able in producing, starting from simple hydrocarbon, compact polycyclic aromatic hydrocarbon molecules presently believed to be abundant constituents in our as well as in other Galaxies.

KeV ion irradiation of frozen benzene layers (-1 pm thick) gives rise to carbonaceous materials. The evolution of atomic structure of benzene leading to the arrangement of graphitic cluster inside the so called "Ion Produced Hydrogenated Amorphous Carbon" films (IPHAC) is discussed. UV-visible, infrared spectroscopy and Elastic Recoil Detection Analysis (ERDA) are used to distinguish the aliphatic and aromatic contribution in the amorphous structure. Application of these results to astrophysics lies in the possibility to explain the observed extended red emission and near-infrared continuum emission in several astronomical objects. Ion irradiation appears also to be able in producing, starting from simple hydrocarbon, compact polycyclic aromatic hydrocarbon molecules presently believed to be abundant constituents in our as well as in other Galaxies.

We report room temperature delamination of chemically vapor deposited diamond films on a Si substrate due to 1.5 MeV He+ ion bombardment. The delamination of films has been studied by scanning electron microscopy. The threshold fluence at which the delamination takes place has been determined in situ by monitoring the hydrogen signal with the help of elastic recoil detection analysis. Micro Raman measurements show the presence of residual stress (1.19 GPa) in the as-prepared films and its relaxation at the peripheri of the delaminated regions. It is proposed that enhancement of the residual stress during He+ ion bombardment leads to stress saturation conditions which result in the delamination of the brittle diamond films from the film/substrate interface. These findings lead to the possibility of creating ion-beam induced channels in diamond films for device isolation by suitable choice of film/substrate combination.

Deuterium and hydrogen migration and release have been studied in stainless steel\ niobium\ palladium during accelerated electrons and 03 N ions[ It was shown that radiation stimulates the intensive release of electrolytically introduced deuterium from stainless steel\ Pd and Nb[ The mechanism release of deuterium from metals under the in~uence of radiation released with accumulative properties of internal D"H# atmosphere and in~uence of ionizing radiation on potential surface barrier preventing formation of D 1 "H 1 #\ molecules and its desorption in gas phase[

Deposition of composite Ti/hydrocarbon plasma polymer films is performed by DC magnetron sputtering of titanium (Ti) target in Ar/n-hexane mixture. Heterogeneous film structure is confirmed. Adhesion, proliferation and maturation of vascular endothelial cells in cultures derived from the bovine pulmonary artery (line CPAE) are studied. The cells are similarly or more active in adhesion, proliferation and maturation than those on glass or pure hydrocarbon plasma polymer.

A new procedure to obtain an online measurement of the beam intensity for charged particle accelerators, as well as the total charge deposited on a target, using a commercial beam profile monitor (BPM) is described in this paper. This procedure can be an alternative to the use of Faraday cups in experiments where their implementation is not feasible.

Barrium fluoride (BaF2) thin films were prepared by electron beam evaporation technique at room temperature, on glass, Silicon and Aluminum substrates having thickness of 20 nm each. Its structural property and surface morphology were studied using glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM) respectively. It was found that grain size, average surface roughness and interface width changes with different substrates. Higuchi algorithm is applied for the fractal measure on AFM images.It was observed found that the fractal dimension varied from substrate to substrate.

Determining the amount of a hydrogen isotope in a material by elastic recoil spectroscopy (ERS) is a routine capability of many laboratories and the data are relatively easy to analyze when only one isotope of hydrogen is present. However, when two or more isotopes of hydrogen are present the analysis is much more complicated. This paper presents data from such samples including a relatively thick sample of erbium hydride with an approximately 2:1 ratio of protium to deuterium and a sample of silicon with ion implanted deuterium that had absorbed hydrogen on the surface. The usual technique of simulation of the data is employed to determine the hydrogen isotope concentration profiles. This is complemented by taking data from the samples at various incident alpha particle beam energies to determine the identity of individual isotopes. This enables use of the variation in stopping power and cross-section with energy to cause, for example, a buried layer of deuterium to be removed from the position in the spectrum where protium from the surface of the sample will overlap the deuterium spectrum.

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Investigation of sputtering of thin diamond-like carbon (DLC) target foils by low energy light ions

We report results of steel substrates coated with hard amorphous carbon and with diamond films. In order to enhance the adherence to the substrate, steel substrates were pretreated by means of a silicon ion beam. Raman spectroscopy was used to analyze the structure of silicon interface while the elastic recoil detection analysis method was applied to determine their composition and thickness. The a-C adherence to the substrate and hardness were also tested. The diamond films were observed by SEM.

AlYB 14 (I mma) thin films were synthesized by magnetron sputtering. On the basis of x-ray diffraction, no phases other than crystalline AlYB 14 could be identified. According to electron probe microanalysis, energy dispersive x-ray analysis and elastic recoil detection analysis, the Al and Y occupancies vary in the range of 0.73-1.0 and 0.29-0.45, respectively. Density functional theory based calculations were carried out to investigate the effect of occupancy on the stability of Al x Y y B 14 (x, y = 0.25, 0.5, 0.75, 1). The mean effective charge per icosahedron and the bulk moduli were also calculated. It is shown that the most stable configuration is Al 0.5 YB 14 , corresponding to a charge transfer of two electrons from the metal atoms to the boron icosahedra. Furthermore, it is found that the stability of a configuration is increased as the charge is homogeneously distributed within the icosahedra. The bulk moduli for all configurations investigated are in the range between 196 and 220 GPa, rather close to those for known hard phases such as α-Al 2 O 3 .

Organosilicon plasma deposited polymers are of interest for different kinds of applications like packaging, passivation and dielectric layers. A large set of plasma processes is possible, among which are low-pressure plasma enhanced chemical vapour deposition (PECVD) and plasma assisted chemical vapour deposition (PACVD) often used. In this work, we studied the composition and surface morphology of the hexamethyldisiloxane (HMDSO) and tetramethyldisiloxane (TMDSO) layers produced by PECVD and PACVD deposition using three plasma generation processes (plasma reactors): RF inductively coupled plasma (RFICP), microwave distributed electron cyclotron resonance plasma (DECR) and microwave induced remote nitrogen afterglow (MIRA). The layer composition was investigated by Rutherford backscattering spectrometry (RBS) and by elastic recoil detection analysis (ERDA) and the layer surface morphology was determined by atomic force microscopy (AFM). Composition, density and morphology (roughness, porosity) of the layers is discussed in connection with deposition techniques used.

Double probe measurements were performed in a microwave plasma at various hydrogen pressures. Electron temperature increases with the growth pressure. Electron density is determined to be 5.6, 7.2 and 8 x 10" cmp3 within 20% accuracy, at 20,40 and 70 Torr, respectively. The dissociation rate of hydrogen increases with pressure. Elastic recoil detection analysis was used to measure the relative H concentration in the films. The stress in the films changes systematically as the H content increases. We find that as 1 h H atom concentration in the plasma increases, the concentration of H in the films goes down.

Torr by HFCVD while keeping the substrate temperature constant. The films were characterised using micro-Raman spectroscopy, X-Ray diffraction (XRD) and scanning electron microscopy GEM). Micro-Raman spectra show a sharp peak centered near the natural diamond line (x 1332 cm-'! accompanied by a non-diamond band at z 1450-1550 cm-'. Intense peaks corresponding to (I I I), (400) and (3 I I) reflections are observed in XRD. Diamond crystallites with sharp facets are seen in SEM. Plasma diagnostics in the MPCVD system were also performed at various conditions in order to estimate the H atom concentration in the gas phase. Elastic recoil detection analysis was used to measure the H concentration. It is observed that the H concentration shows contrasting trends in the films grown by MPCVD and HFCVD at various growth pressures. H concentration is found to be 1.0, 0.8 and 0.7at % in the films grown at 20, 40 and 70 Torr, respectively, in MPCVD apparatus. Conversely, the H concentration in the films grown by HFCVD increases systematically with growth pressure (0.5, I. I and I.4 at % at 40, 100 and 140 Torr, respectively). Non-diamond carbon impurities correlate well with H content, Results of micro-Raman spectroscopy, SEM and plasma diagnostic are discussed in the framework of a growth model. Results of H content in the diamond films obtained by various techniques are compared.

Diamond thin films were grown on silicon substrates using microwave plasma chemical vapour deposition at various microwave power densities (MPD). Three sets of the films were grown for various thicknesses. The films were characterised using micro-Raman spectroscopy, photoluminescence (PL), cathodoluminescence (CL) and X-ray photoelectron spectroscopy (XPS). Elastic recoil detection', analysis (ERDA) was used to determine concentrations of light impurities (N and O). Micro-Raman spectroscopy shows a systematic variation in the non-diamond to diamond carbon content with MPD. Various defect centers related mainly with nitrogen were observed in PL and CL spectra of the films. A sharp feature was observed at 1.68 eV in all the spectra. This peak is attributed to Si impurity in diamond films. Interestingly, the intensity of the peak increases with increase in MPD. The broad band A in the CL spectra has contributions from both green and blue regions, and the intensity ratio of the green to blue region varies with MPD. The spectra of the films of various thickness were also compared, and it was found that the Si content of the films decreases with increasing thickness. ERDA results indicate that the films contain 0.1-0.6% N and O as impurities. The interface composition of the films as a function of MPD was investigated using XPS. and the increase in the Si content of" the films was correlated with the change in composition of the diamond/silicon interface. ~, 1998 Elsevier Science S.A.

Even at low fluences doping of quartz by ion implantation results in amorphization. Here we report on the measurement of cathodoluminescence and surface structures during solid phase epitaxy in Na-implanted a-quartz annealed in 18 O 2 atmosphere. Complete epitaxy was achieved under appropriate conditions of ion fluence, annealing temperature and time. The crystalline structure of the samples was studied by Rutherford backscattering channelling spectroscopy and the 18 O-16 O exchange between the matrix and 18 O 2 annealing gas by elastic recoil detection analysis. In the cathodoluminescence spectra taken at room temperature, five bands were identified and assigned to various defect centres. Two of the bands in the violet region at 3.25 and 3.65 eV strongly vary in intensity at 843-1173 K annealing temperature and appear to be intimately correlated with the presence of Na-ions in the implanted region of the matrix. Finally, atomic force microscopy enabled, for the first time, the observation of the correlation of surface structures and epitaxy.

The measured profiles of a high resolution elastic recoil detection (ERD) analysis utilizing electrostatic or magnetic spectrographs may contain artefxts if only one charge state is measured. This effect is demonstrated by the analysis of 31.8 MeV "Cq+ recoil ions of different charge states q+ scattered from a pure graphite sample using 60 MeV "Nix' ions at a scattering angle of 15" and by the analysis of a thin BN film. The primary charge state distribution obtained from scattering events very near the surface significantly deviates from the equilibrium one which is measured for carbon ions scattered deeper than 10" at/cm' below the surface. Charge exchange cross sections between the main charge states are obtained analysing the depth dependent charge state distributions.

Compositional analysis of aluminium oxy-nitride (AlON) films deposited by reactive magnetron sputtering was performed using time-of-flight elastic recoil detection analysis (ToF-ERDA) and X-ray photoelectron spectroscopy (XPS) with sputter profiling. The composition profiles of the films depend on deposition conditions. The benefits of the different analytical methods are discussed and comparison of the profiles is performed. Conversion of the depth scale from XPS sputter time to a nm scale is implemented and the ToF-ERDA profile fitted. Densities of the deposited AlON films are calculated indicating differing film quality in agreement with the composition profile extracted.

We measured the temperature dependence of the probability of small heating and total losses of UCNs on the PFPE Fomblin Y surface with various molecular mass MW (2800, 3300, 6500 amu) in the temperature range of 100-300 K. The probability of small heating sharply decreases with increasing MW and decreasing temperature. The probability of total loss weakly decreases with decreasing temperature and takes the minimum value at MW = 3300 amu. As this oil provides a homogeneous surface with minimal probabilities of small heating and total losses of UCNs, it is the preferred candidate for experiments on measuring the neutron lifetime.

We measured the temperature dependence of the probability of small heating and total losses of UCNs on the PFPE Fomblin Y surface with various molecular mass MW (2800, 3300, 6500 amu) in the temperature range of 100-300 K. The probability of small heating sharply decreases with increasing MW and decreasing temperature. The probability of total loss weakly decreases with decreasing temperature and takes the minimum value at MW = 3300 amu. As this oil provides a homogeneous surface with minimal probabilities of small heating and total losses of UCNs, it is the preferred candidate for experiments on measuring the neutron lifetime.

Hydrogen embrittlement is often a catastrophic phenomenon of machine elements failure under cyclic stresses. This hydrogen is generated as a result of tribo-chemical and mechanical actions on the working surfaces. This hydrogen can have three different zones or stages of behaviour under tribo-mechanical actions. Firstly, it can strongly adsorb on the mating surfaces at a shallow subsurface zone and take up the load in the boundary-lubricating regime and reduce the coefficient of friction. At a second stage, it can diffuse to the deep subsurface zone where it might work together with Hertzian stresses and embrittle the subsurface zone. The last zone of hydrogen activity is the bulk of the bearing steel where it is known to collect under the action of tensile stresses and degrade the bearing steel and hence resulting in catastrophic failure. It is important and interesting to follow up the presence of hydrogen in these zones in order to predict the safe functioning of the machine elements. In addition to this a clear distinction must be made between the internal hydrogen embrittlement and environmental hydrogen embrittlement. Two important behaviours of hydrogen are studied and quantification was made by a melting sample technique. Dependence of hydrogen diffusion on the variation of tribo-mechanical action is shown in this work. This was done by studying the pure rotating bending, rotating bending with combination of sliding and rolling motion of the mating surfaces and uni-axial tensile experiments in pure water environment to see the diffusion of hydrogen into or out of the AISI-52100 bearing steel and in silver steel. Two different approaches were adopted in order to investigate the presence of hydrogen in three zones under the action of different stress states. The two techniques are melting sample technique by using hydrogen analyser and elastic recoil detection analysis, an ion beam technique. It is believed until now that hydrogen spread is homogeneous in the bearing steel. The results obtained showed that the inherent amount of hydrogen in steel samples is non-homogeneous and it was learnt that inherent amount of hydrogen in the steel samples is very important in order to support the boundary lubrication by hydrogen. Content of hydrogen in the steel samples showed a relation to the increasing number of cyclic stresses. The sliding-rotating bending stress state showed a considerable wear of the surfaces but the content of hydrogen was not very high in that sample when compared to the samples that were run under pure rotating bending stress state.

The dielectric functions of amorphous and polymorphous silicon films prepared under various plasma conditions have been deduced from UV-visible spectroscopic ellipsometry measurements. The measured spectra have been first simulated by the use of the Tauc-Lorentz dispersion model and then the compositions of the films have been obtained by the use of the tetrahedron model combined with the Bruggeman effective medium approximation. This approach allows us to determine the hydrogen content, the crystalline fraction, and the void fraction of the films. This is particularly important in the case of polymorphous films in which the low crystalline fraction ͑below 10%͒ can only be detected when an accurate description of the effects of hydrogen on the dielectric function through the tetrahedron model is considered. The hydrogen content and film porosity deduced from the analysis of the spectroscopic ellipsometry measurements are in excellent agreement with the hydrogen content and film density deduced from combined elastic recoil detection analysis and Rutherford backscattering spectroscopy measurements. Moreover, despite their high hydrogen content ͑ϳ15%-20%͒ with respect to hydrogenated amorphous silicon films deposited at the same temperature ͑8%͒, polymorphous silicon films have a high density, which is related to their very low void fraction.

In this paper, we investigate on the presence of hydrogen and nitrogen related infrared absorptions in chemical vapour deposited (CVD) diamond films. Investigations were carried out in cross sections of diamond windows, deposited using hot filament CVD (HFCVD). The results of Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) and Raman spectroscopy carried out in a cross section of self-standing diamond sheets are presented. The FTIR spectra showed several features that have not been reported before. In order to confirm the frequency of nitrogen related vibrations, ab-initio calculations were carried out using GAMESS program. The investigations showed the presence of several C-N related peaks in one-phonon (1000-1333 cm À 1). The deconvolution of the spectra in the three-phonon region (2700-3150 cm À 1) also showed a number of vibration modes corresponding to sp m CH n phase of carbon. Elastic recoil detection analysis (ERDA) was employed to compare the H content measured using FTIR technique. Using these measurements we point out that the oscillator strength of the different IR modes varies depending upon the structure and H content of CVD diamond sheets.

Recent emergence of Mg as a promising hydrogen storage material with 7.6 wt% hydrogen encourages study on its thin films to understand physics of storage mechanism. The present study investigates the variations in hydrogen storage properties of Pd sandwiched Mg films upon introduction of Al layer. Multilayered stack of Pd/Mg/Pd and Pd/Al/Mg/Pd were grown on Si substrate using vapor deposition method and further hydrogenated at 150 C under 2 bar H 2 pressure for 2 h. Elastic Recoil Detection Analysis (ERDA) technique with 120 MeV Ag 9þ ions was used to obtain hydrogen concentration versus incident ion fluence. ERDA study reveals that Pd/Mg/Al/Pd films absorb 6.01 Â 10 18 hydrogen atoms/cm 2 in comparison to 4 Â 10 17 atoms/cm 2 absorbed by Pd/Mg/Pd system. Atomic force Microscopy (AFM) and X-ray Diffraction (XRD) techniques were utilized to analyze the morphological and structural changes in the hydrogenated films. Results indicate that addition of Al to the base system has led to the formation of Mg(AlH 4) 2 along with MgH 2 causing an increment in the hydrogen storage capacity and reduction in the oxygen content.

Mesoporous sol-gel silica thin films were irradiated with gold ions of medium energies from 0.5 MeV to 12 MeV. In all cases these porous materials are compacted as a result of mesopore collapse and deformation. X-ray reflectivity and SEM measurement show that the total compaction (densification) is achieved for a fluence of about 2 Â 10 14 cm À2 (~5 Â 10 21 keV cm À3). The process of mesoporosity collapse seems different according to the irradiation regime (nuclear versus electronic). This effect results in a Ushaped evolution of the curve of the damage cross section as a function of the energy of ions Au. Infrared measurement of Au 0.5 MeV irradiated samples show a shift of TO 3 band towards lower wavenumber, related to Si-O-Si bond angle and Si-O bond length change. The sol-gel mesoporous and nonporous samples exhibit a delayed shift compared to thermal nonporous ones, which indicates that sol-gel materials are more radiation tolerant from this point of view. The sensitivity of these mesoporous structures to the damage caused by irradiation opens interesting prospects for obtaining selfconditioning materials.

The addition of silicon to hydrogenated amorphous carbon can have the advantageous effect of lowering the compressive stress, improving the thermal stability of its hydrogen, and maintaining a low friction coefficient up to high humidity. Most experiments to date have been on hydrogenated amorphous carbon–silicon alloys (a-C1−xSix:H) deposited by rf plasma enhanced chemical vapor deposition. This method gives alloys with sizeable hydrogen content and only moderate hardness. Here we use a high plasma density source known as the electron cyclotron wave resonance source to prepare films with higher sp3 content and lower hydrogen content. The composition and bonding in the alloys is determined by x-ray photoelectron spectroscopy, Rutherford backscattering, elastic recoil detection analysis, visible and ultraviolet (UV) Raman spectroscopy, infrared spectroscopy, and x-ray reflectivity. We find that it is possible to produce relatively hard, low stress, low friction, almost humidity insen...

The astrophysical S-factor for the 11 B(p, α)2α reaction has been evaluated at effective center of mass (CM) energies of 110, 113, 115, 117, 119, 121, 124, 126, 128, 131, and 133 keV. It was observed that there was a significant difference between the calculated values and the literature values. Another difference with literature is the increased yield ratio N0/N1 of the reaction channels 11 B(p,α0) 8 Be and 11 B(p,α1) 8 Be with increasing energy. The reason for the discrepancy was attributed to being carbon build-up on the target surface during irradiation. Due to the Carbon build-up effect in the energy range studied, effective energy (Eeff) values for the 11 B(p, α)2α reaction decreased by about 30 keV.

Nanocrystalline Pd-capped Mg films were prepared by e-beam evaporation and hydrided/ deuterated in order to investigate the hydride decomposition mechanism. To that aim, different techniques were used (XRD, FEG, TPDeMS, isotope exchange and "in situ" desorption optical measurements). Obtained results show that hydride films decomposed at T ¼ 165 C by a process controlled by the Mg/MgH 2 interface reaction with an activation energy E a ¼ 136 AE 5 kJ/mol H 2. Interface is located into each MgH 2 nanocrystallite according to RBS (Rutherford Backscattering) and ERDA (Elastic Recoil Detection Analysis) measurements performed during hydride decomposition. Moreover, RBS and ERDA spectra also show the formation of a Mg x Pd y intermixed region. This intermixed region does not modify the type of control mechanism but increases the activation energy of the desorption process and slows down further hydrogenation events.

Eect of 100 MeV Ag ion irradiation on 57 Co-doped CuO has been studied using X-ray diraction, M ossbauer spectroscopy and elastic recoil detection analysis. Irradiation leads to a substantial oxygen loss in the sample. X-ray diraction measurements show a considerable damage production in the CuO lattice up to a depth much larger than the range of the bombarding ions. The sample gets amorphized up to the penetration depth of Ag ions. The Neel temperature of the damaged portion of the sample is considerably decreased. The annealing behaviour of the amorphized region is characterized by a broad distribution of activation energies.

We investigate the growth and structure properties of Mg:C thin films. The films are prepared using a dc magnetron sputtering discharge where the electrical resistance over the films is monitored during growth in-situ with a four point probe setup. The structural properties of the films are investigated using X-ray diffraction measurements and the elemental composition and binding in the films is determined using elastic recoil detection analysis and X-ray photoelectron spectroscopy. The results show that during co-sputtering the carbon flux influences the initial stages of the film growth. The films are made of polycrystalline magnesium grains embedded in a carbon network, the size of which depends on the carbon content, but amorphous phases cannot be excluded. The XPS measurements show the presence of carbidic carbon whereas X-ray measurements find no Mg:C phases. The overall stability of the films is found to depend on the carbon content, where stable films capped with a 14 nm Pd layer cannot be obtained with carbon content above 18%.

Knowledge of radiation-induced helium bubble nucleation and growth in SiC is essential for applications in fusion and fission environments. Here we report the evolution of microstructure in nanoengineered (NE) 3C SiC, pre-implanted with helium, under heavy ion irradiation at 700 °C up to doses of 30 displacements per atom (dpa). Elastic recoil detection analysis confirms that the as-implanted helium depth profile does not change under irradiation to 30 dpa at 700 °C. While the helium bubble size distribution becomes narrower with increasing dose, the average size of bubbles remains unchanged and the density of bubbles increases somewhat with dose. These results are consistent with a long helium bubble incubation process under continued irradiation at 700 °C up to 30 dpa, similar to that reported under dual and triple beam irradiation at much higher temperatures. The formation of bubbles at this low temperature is enhanced by the nano-layered stacking fault structure in the NE SiC, which enhances point defect mobility parallel to the stacking faults. This stacking fault structure is stable at 700 °C up to 30 dpa and suppresses the formation of dislocation loops normally observed under these irradiation conditions.

Anode-supported cells comprising a three layer structure of a porous composite cathode of Sr-doped LaMnC>3 (LSM) + yttria-stabilized zirconia (YSZ); a thin, dense YSZ electrolyte; and a porous Ni + YSZ anode were fabricated. The anode thickness was varied between-1.04 and-3.86 mm. The YSZ electrolyte thickness was-10 pm and the LSM + YSZ cathode thickness was-50 pm. The cells were tested at 800°C with humidified hydrogen as the fuel and air as the oxidant. The voltage (V) vs. current density (i) traces were nonlinear; concave-up {d2 V I di2 > oj at low current densities and convex-up (d2V I di2 < oj at high current densities. The maximum power density for a cell with an anode thickness of-1.04 mm was-1.9 W/cm2 and that for a cell with an anode thickness of-3.86 mm was-1.1 W/cm2. The measured short circuit current densities were-6.35 A/cm2 for a cell with an anode thickness of-1.04 mm and-3.56 A/cm2 for a cell with an anode thickness of-3.86 mm. The V vs. i traces were fitted to a previously developed theoretical model. The present work shows that anode-supported cells can be made with a relatively thick and rugged anode while still exhibiting an excellent power density at a temperature of 800°C.

Anode-supported cells comprising a three layer structure of a porous composite cathode of Sr-doped LaMnC>3 (LSM) + yttria-stabilized zirconia (YSZ); a thin, dense YSZ electrolyte; and a porous Ni + YSZ anode were fabricated. The anode thickness was varied between-1.04 and-3.86 mm. The YSZ electrolyte thickness was-10 pm and the LSM + YSZ cathode thickness was-50 pm. The cells were tested at 800°C with humidified hydrogen as the fuel and air as the oxidant. The voltage (V) vs. current density (i) traces were nonlinear; concave-up {d2 V I di2 > oj at low current densities and convex-up (d2V I di2 < oj at high current densities. The maximum power density for a cell with an anode thickness of-1.04 mm was-1.9 W/cm2 and that for a cell with an anode thickness of-3.86 mm was-1.1 W/cm2. The measured short circuit current densities were-6.35 A/cm2 for a cell with an anode thickness of-1.04 mm and-3.56 A/cm2 for a cell with an anode thickness of-3.86 mm. The V vs. i traces were fitted to a previously developed theoretical model. The present work shows that anode-supported cells can be made with a relatively thick and rugged anode while still exhibiting an excellent power density at a temperature of 800°C.

Numerous experimental studies for near-surface analyses of B in Si have shown that the B distribution within the top few nanometers is distorted by secondary ion mass spectrometry (SIMS) depth profiling with O 2-flooding or normal incidence O 2 bombardment. Furthermore, the presence of surface oxide affects the X j determination as well as B profile shape when SIMS analyses are conducted while fully oxidizing the analytical area. Nuclear techniques such as elastic recoil detection (ERD), nuclear reaction analysis (NRA), and highresolution Rutherford backscattering spectrometry (HR-RBS), are known to provide a profile shape near the surface that is free of artifacts. Comparisons with SIMS analyses have shown that SIMS analyses without fully oxidizing the analytical area agree well with these techniques at sufficiently high concentrations (where the nuclear techniques are applicable). The ability to measure both the B profile and an oxide marker with this non-oxidizing SIMS technique also allows accurate positioning of the B profile with respect to the SiO 2 /Si interface. This SIMS analysis protocol has been used to study the differences in near-surface dopant distribution for plasma-based implants. This study specifically focuses on measuring near-surface profile shapes as well as total implant doses for ultra-shallow B implants in Si especially those made with high peak B concentrations.

Diamond thin films were grown on silicon substrates using microwave plasma chemical vapour deposition at various microwave power densities (MPD). Three sets of the films were grown for various thicknesses. The films were characterised using micro-Raman spectroscopy, photoluminescence (PL), cathodoluminescence (CL) and X-ray photoelectron spectroscopy (XPS). Elastic recoil detection', analysis (ERDA) was used to determine concentrations of light impurities (N and O). Micro-Raman spectroscopy shows a systematic variation in the non-diamond to diamond carbon content with MPD. Various defect centers related mainly with nitrogen were observed in PL and CL spectra of the films. A sharp feature was observed at 1.68 eV in all the spectra. This peak is attributed to Si impurity in diamond films. Interestingly, the intensity of the peak increases with increase in MPD. The broad band A in the CL spectra has contributions from both green and blue regions, and the intensity ratio of the green to blue region varies with MPD. The spectra of the films of various thickness were also compared, and it was found that the Si content of the films decreases with increasing thickness. ERDA results indicate that the films contain 0.1-0.6% N and O as impurities. The interface composition of the films as a function of MPD was investigated using XPS. and the increase in the Si content of" the films was correlated with the change in composition of the diamond/silicon interface. ~, 1998 Elsevier Science S.A.

Lanthanide aluminosilicate glasses have been developed for their high mechanical properties. Nevertheless, little is known about their chemical durability and the role of rare-earth elements on the dissolution mechanisms of such glasses. This type of glass appears to be a suitable complement waste forms of borosilicate glass for the speci®c immobilisation of trivalent actinides. The ®rst part of this paper deals with the synthesis and the characterisation of glasses in the system SiO 2 ±Al 2 O 3 ±Y 2 O 3 ±Ln 2 O 3 (with Ln La or Ce) and the second part with the study of their leachability in deionised water using a re¯ux column at 100°C. Hydrated glass surfaces have been examined with scanning electron microscopy coupled with X-ray microanalysis and nuclear microanalysis. Leachates have been characterised by using ICP-MS and UV-visible spectrophotometry. After leaching, the formation of a surface layer slightly depleted in Si and Al and containing Y and La hydroxicarbonates and hydroxides is discussed.

An analytical procedure and a simulation-optimization algorithm are described for hydrogen determination based on elastic recoil detection induced by low-energy 4He ions (I 3 MeV) using transmission geometry. Hydrogen concentration depth profiles can be derived from the experimental recoil spectra for a depth range of up to 6 pm with a resolution better than 40 nm at the surface. The method is applied to thin polyimide films irradiated by high-energy heavy ions. The 3D hydrogen distribution is determined with a 4He+ microbeam. A high-hydrogen-concentration xone below the surface is shown. The hydrogen distribution is seen ,to evolve during the 4He+ irradiation.

A possible correlation between observed surface electrical degradation in three types of alumina under ion bombardment and changes in luminescence emission has been examined by in situ sequential measurement of ion beam induced luminescence and electrical conductivity. Common luminescence bands are observed at 340, 410, and 695 nm corresponding to F + , F and Cr 3+ together with additional impurity related emissions for each material. Rapid changes in these emission bands occur as a precursor to measurable surface electrical degradation, justifying the interest in the study of this technique as a potential monitoring tool for material evolution and degradation during irradiation.

Rutherford backscattering spectrometry (RBS) is an ion beam based analytical technique giving information on the atomic composition profile of the near surface region of materials. As the physical processes involved in this technique are very well understood, computer codes have been developed providing simple and efficient means of performing quantitative RBS analysis. Moreover, with this technique it is possible, in principle, to perform absolute measurements although the task is not an obvious one. The attainable accuracy in the measurements is limited, among other factors by the uncertainty in the current knowledge of the stopping. power of materials for a-particles of MeV energy. The shape of an RBS spectrum from which an energy/depth relation and a yield/composition relation has to be extracted is dependent on the stopping power values, and its uncertainty directly affei;ts the attainable accuracy of the analytical information of the spectrum. In this contribution we show evidence of the inaccuracies of the approximated stopping powers in the computer code RUMP for the matrix element Si by direct use of Harwell II standard samples in a RBS experiment, and show how these inaccuracies can affect the interpretation of the results in a RBS analysis.

The absolute amount of deuterium in amorphous deuterated carbon (a-C:D) layers has been measured by six laboratories with dierent techniques, such as MeV ion beam analysis, secondary ion mass spectrometry (SIMS), and thermal desorption spectrometry (TDS). The a-C:D layers have been deposited from a CD 4 glow discharge plasma onto carbon and silicon substrates. The results for the absolute numbers obtained with the dierent analysing techniques show a scatter of up to about 35% around the average value. These deviations are larger than the errors stated by the experimentalists and indicate possible systematic uncertainties in some of the measurements.