摘要:

Plasma‐based ion implantation and deposition (PBII&D) technology has been developed rapidly in the past decade. This technique is especially promising for modifying three‐dimensional components. In PBII&D, plasma is generated in the entire processing chamber and then surrounds the components. When a train of negative voltage pulses are applied to the parts, ions are drawn to all the surfaces exposed to the plasma. At a high energy, ions are implanted to the surfaces, but at a low energy and with a proper precursor gases, ions are deposited to form a film. This technology has found applications in many areas including semiconductors, automotive, aerospace, energy and biomedical. This article reviews PBII&D fundamentals, describes features of various PBII&D systems and plasma sources, and discusses implantation and deposition techniques. The paper will also present application examples of this technology. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843501

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Surface treatment by means of pulsed laser beams in reactive atmospheres is an attractive technique to enhance the surface features, such as corrosion and wear resistance or the hardness. Many carbides and nitrides play an important role for technological applications, requiring the mentioned property improvements. Here we present a new promising fast, flexible and clean technique for a direct laser synthesis of carbide and nitride surface films by short pulsed laser irradiation in reactive atmospheres (e.g. methane, nitrogen). The corresponding material is treated by short intense laser pulses involving plasma formation just above the irradiated surface. Gas‐Plasma‐Surface reactions lead to a fast incorporation of the gas species into the material and subsequently the desired coating formation if the treatment parameters are chosen properly. A number of laser types have been used for that (Excimer Laser, Nd:YAG, Ti:sapphire, Free Electron Laser) and a number of different nitride and carbide films have been successfully produced. The mechanisms and some examples will be presented for Fe treated in nitrogen and Si irradiated in methane. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843502

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

JANNUS(Joint Accelerators for Nano‐Science and Nuclear Simulation) is a project designed to study the modification of materials using multiple ion beams and in‐situ TEM observation. It will be a unique facility in Europe for the study of irradiation effects, the simulation of material damage due to irradiation and in particular of combined effects. The project is also intended to bring together experimental and modelling teams for a mutual fertilisation of their activities. It will also contribute to the teaching of particle‐matter interactions and their applications.JANNUSwill be composed of three accelerators with a common experimental chamber and of two accelerators coupled to a 200 kV TEM. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843503

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Swift heavy ions with energies of about 5 MeV/u cause a high energy deposition into solid targets. As a consequence first the electronic system receives energy and afterwards the energy is transferred to the atomic system by electron phonon coupling or Coulomb repulsion. After a short introduction of what is denoted ion track, different approaches for investigating the ion track formation are presented. Typical experimental data corresponding to these approaches are discussed with respect to the thermal‐spike and Coulomb‐explosion models. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843504

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The deposition of carbon on metals is the unavoidable consequence of the application of different wall materials in present and future fusion experiments like ITER. Presently used and prospected materials besides carbon (CFC materials in high heat load areas) are tungsten and beryllium. The simultaneous application of different materials leads to the formation of surface compounds due to the erosion, transport and re‐deposition of material during plasma operations. The formation and erosion processes are governed by widely varying surface temperatures and kinetic energies as well as the spectrum of impinging particles from the plasma. The knowledge of the dependence on these parameters is crucial for the understanding and prediction of the compound formation on wall materials. The formation of surface layers is of great importance, since they not only determine erosion rates, but also influence the ability of the first wall for hydrogen isotope inventory accumulation and release. Surface compound formation, diffusion and erosion phenomena are studied under well‐controlled ultra‐high vacuum conditions using in‐situ X‐ray photoelectron spectroscopy (XPS) and ion beam analysis techniques available at a 3 MV tandem accelerator. XPS provides chemical information and allows distinguishing elemental and carbidic phases with high surface sensitivity. Accelerator‐based spectroscopies provide quantitative compositional analysis and sensitivity for deuterium in the surface layers. Using these techniques, the formation of carbidic layers on metals is studied from room temperature up to 1700 K. The formation of an interfacial carbide of several monolayers thickness is not only observed for metals with exothermic carbide formation enthalpies, but also in the cases of Ni and Fe which form endothermic carbides. Additional carbon deposited at 300 K remains elemental. Depending on the substrate, carbon diffusion into the bulk starts at elevated temperatures together with additional carbide formation. Depending on the bond nature in the carbide (metallic in the transition metal carbides, ionic e.g. in Be2C), the surface carbide layer is dissolved upon further increased temperatures or remains stable. Carbide formation can also be initiated by ion bombardment, both of chemically inert noble gas ions or C+or CO+ions. In the latter case, a deposition‐erosion equilibrium develops which leads to a ternary surface layer of constant thickness. A chemical erosion channel is also discussed for the enhanced erosion of thin carbon films on metals by deuterium ions. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843505

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The broad maximum in the energy spectra of Ar+ions scattered from the clean metal surfaces to the scattering angles smaller than 90° is studied. Besides the Ar+ions, other ion species (He+, N+and Ne+) are also used as projectiles. The targets in the experiments were polycrystalline silver and copper as well as the monocrystalline nickel (110). According to the analysis of the obtained energy spectra, the maximum is interpreted as the consequence of the symmetric binary collisions between the Ar+projectiles and the former implanted Ar atoms placed under the outermost atomic layer. This type of experiments gives a unique opportunity to study the process of low energy Ar+ions implantation in real time, and it could be extended to other projectile‐target systems of the greater technological interest. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843506

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The experimental system that enables thin film deposition by chemical vapor deposition combined with magnetron sputtering and sample surface characterization by photoelectron spectroscopy (PES), without breaking the vacuum between the deposition and the characterization stage, is described. The particular goal of this work was study of the surface arrangement of embedded metallic nanoclusters of 1B group (Au, Ag, and Cu) in amorphous hydrogenated carbon (a‐C:H). From the range of applied material characterization tools, we present here the results of several PES‐based experiments used to reveal cluster properties at the surface: as‐deposited sample PES measurements, off‐normal take‐off angle XPS, andin situin‐depth XPS profiling by Ar+ion etching. Clear distinction in all PES results of the samples deposited on the grounded substrates from those deposited on −150 V dc biased ones is obtained, revealing that keeping the substrate grounded during deposition results in topmost metallic clusters covered with a very thin layer ofa‐C:H, while applying negative bias voltage to the substrate results in partially bald clusters on the surface. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843507

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A part of incident energy is absorbed within the irradiated sample when a solid is exposed to the influence of laser radiation, to more general electromagnetic radiation within the wide range of wavelengths (from microwaves, to infrared radiation to X‐rays), or to the energy of particle beams (electronic, protonic, or ionic). The absorption process signifies a highly selective excitation of the electronic state of atoms or molecules, followed by thermal and non‐thermal de‐excitation processes. Non‐radiation de‐excitation‐relaxation processes induce direct sample heating. In addition, a great number of non‐thermal processes (e.g., photoluminescence, photochemistry, photovoltage) may also induce heat generation as a secondary process. This method of producing heat is called the photothermal effect.The photothermal effect and subsequent propagation of thermal waves on the surface and in the volume of the solid absorbing the exciting beam may produce the following: variations in the temperature on the surfaces of the sample; deformation and displacement of surfaces; secondary infrared radiation (photothermal radiation); the formation of the gradient of the refractivity index; changes in coefficients of reflection and absorbtion; the generation of sound (photoacoustic generation), etc. These phenomena may be used in the investigation and measurement of various material properties since the profile and magnitude of the generated signal depend upon the nature of material absorbing radiation. A series of non‐destructive spectroscopic, microscopic and defectoscopic detecting techniques, called photothermal methods, is developed on the basis of the above‐mentioned phenomena.This paper outlines the interaction between the intensity modulated laser beam and solids, and presents a mathematical model of generated thermal sources. Generalized models for a photothermal response of optically excited materials have been obtained, including thermal memory influence on the propagation of thermal perturbation. Focus is on optically opaque media. The derived models are compared to existing models neglecting the thermal memory effect. In this way it has been possible to determine the range of value of existing models and to indicate the additional employment of photothermal methods in determining through experimentation the thermal memory properties of solids. These properties have not as yet been experimentally determined in any medium, nor has the methodology for the experimental measurement of thermal memory parameters been suggested in the literature. Their recognition is highly significant not only for further fundamental research, but for many modern applications as well. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843508

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

If swift heavy ions (5 MeV/u) hit solid targets energy is transferred to the electrons of the solid. Caused by the high electronic energy deposition along the flight path of the ion a cylindrical shaped chemical or structural defect cluster is formed. This kind of defect cluster together with its electronic and atomic precursors is called ion track. Ion‐track formation is mainly described by two different mechanisms: At the beginning of the ion‐track formation, within a timescale of 10−17s, the energy is transferred into the electronic system and the electrons move away from the center of the track where a positively charged inner cylinder remains. If the charge‐neutralization time of these positive ions along the track is sufficiently long so that they can repel each other by Coulomb forces, the Coulomb‐explosion model can describe the track formation. Otherwise (short charge‐neutralization time) the energy is transferred into the atomic system by electron‐phonon coupling (within a picosecond timescale), what is included in the thermal‐spike model. During the energy transfer from the electronic to the atomic system atoms are set in motion and charged as well as neutral particles are sputtered. By detecting these particles energy resolved information on the track forming mechanism can be achieved.Within the talk different experimental approaches to the ion‐track formation realized in the ion‐beam laboratory (ISL) of the Hahn‐Meitner‐Institut (HMI) are presented.Theelectron dynamicstakes place within a femtosecond timescale. Auger‐electrons leaving the target surface are suitable for investigating the short‐time dynamics because typical Auger‐decay times are in the order of a few femtoseconds. The width of the Auger‐profiles mainly reflects a convolution of the energy distribution of the electrons involved in the Auger process. An energy transfer from the projectile to the electronic system of the target causes a change of the energy distribution of the valence electrons and the shape of Auger‐profiles respectively.For analyzing theatom dynamics(picosecond timescale) sputtered ions as well as neutral particles have to be detected. The desorbed ions are detected by a conventional energy resolved mass‐spectrometer. For the detection of the sputtered neutrals a new experimental setup is installed. The neutrals are ionized by non‐resonant multiphoton ionization with an amplified pulsed Ti:Sapphire laser and analyzed by a time‐of‐flight mass spectrometer. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843509

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Three atomic spectroscopic databases of the U.S. National Institute of Standards and Technology are reviewed. First, our principal spectroscopic database, the Atomic Spectra Database (ASD), is discussed, which will soon be put on the internet in a new, entirely redesigned and expanded version 3.0. This new edition will include several additional critical compilations that were recently completed at NIST. Furthermore, two new smaller specialized databases will be reviewed, — a handbook of basic atomic spectroscopic data and a tabulation of data for soft x‐ray lines, tailored to the needs of x‐ray space observatories. Finally, an overview of our plans for new critical data compilations during the next two‐to‐three years will be presented. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1843510

出版商:AIP    

年代:1904

数据来源: AIP