Cylindrical spike model for the formation of diamondlike thin films by ion deposition

T /n_S of n_T rearrangements and n_S atoms in the spike volume as the crucial parameter characterizing the ability of a given ion–target combination to achieve complete rearrangement of the spike volume. n_T/n_S>1 is the optimum condition for diamondlike film growth. For aC films the ion energy dependence of n_T/n_S agrees well with the measured sp³ bond fraction. For Ar⁺-ion-assisted deposition of aC we find n_T/n_S>1 above 50 eV with no pronounced ion energy dependence. Furthermore, our model predicts optimum conditions for the formation of cubic boron nitride between 50 eV and 3 keV. Accepted: 14 October 1997     

Recent trends and open issues in reverse engineering

This paper discusses recent trends in the field of reverse engineering, particularly those highlighted at the Second Working Conference on Reverse Engineering, held in July 1995. The trends observed include increased orientation toward tasks, grounding in complex real-world applications, guidance from empirical study, analysis of non-code sources, and increased formalization. The paper also summarizes open research issues and provides pointers to future events and sources of information in this area.     

Surface characterization of fluorinated polymers (PTFE, PVDF, PFA) for use in ultratrace analysis

Surface characterization of new unused PTFE, PFA and PVDF labware has been carried out by light microscopy, scanning electron microscopy, profilometry and atomic force microscopy. It has been found that in spite of higher micro-roughness, PFA exhibits the lowest nano-roughness and hence seems best suited as vessel material for relatively mild pressureless chemical operations for sample preparation of ultrapure substances, as container material for storage of ultrapure liquids, and for transport of such liquids, e.g., from the producer in the chemical to the end user in the microelectronics industry. This suitability refers only to the surface quality of the investigated materials. PTFE-surfaces, due to the sintering process of production, exhibit the most unfavourable surface quality of the investigated fluorinated polymers.     

Two-dimensional micelle formation of polystyrene-poly(vinylpyridine) diblock copolymers on mice surfaces

We have used atomic force microscopy to study the adsorption of PolyStyrene-Poly(VinylPyridine) (PS-PVP) block copolymers from a selective solvent onto atomically smooth mica surfaces. At certain copolymer concentrations, we observe a highly regular array of spherical surface micelles covering macroscopic areas of the substrate surface. Evidence is given for a thin homogeneous layer underneath the micelles which is probably due to adsorption of free copolymer chains and brush formation prior to the formation of the micellar structures. We discuss the quality of the self-assembled structures regarding different types of defects and try to identify means for improving the long range periodicity of the structures.     

Proximity effect in superconductor/ferromagnet layered system: Influence of superconductivity on magnetic properties of Nb/Fe epitaxial bilayers

Magnetic and superconducting properties of Fe/Nb epitaxial bilayers have been studied. Single crystal Fe/Nb (110) bilayers with a Nb thicknessd _Nb in the range from 250 to 650 Å and with a Fe thicknessd _Fe in the range from 7 to 27 Å were prepared using molecular beam epitaxy techniques. Magnetization measurements showed the existence of a magnetically “dead” Fe-interface layer with a thicknessd _NM varying strongly with minor modifications of the growth conditions. For bilayers with a small magnetic layer thicknessd _M and a smalld _NM the FMR measurements revealed an anomalous decrease of the effective magnetization 4πM _eff of the ferromagnetic Fe layer below the superconducting transition temperatureT _c. The absolute change of 4πM _eff belowT _c depends strongly on the actual values ofd _M andd _NM: upon decreasing bothd _M andd _NM the effect increases considerably. As a possible mechanism for the anomalous temperature dependence of 4πM _eff belowT _c we discuss a spatial modulation of ferromagnetic order due to a modification of the RKKY inter-action in the superconducting state.     

Bell's theorem based on a generalized EPR criterion of reality

First, the demonstration of Bell's theorem, i.e., of the nonlocal character of quantum theory, is spelled out using the EPR criterion of reality as premises and a gedankenexperiment involving two particles. Then, the EPR criterion is extended to include quantities predicted almostwith certainty, and Bell's theorem is demonstrated on these new premises. The same experiment is used but in conditions that become possible in real life, without the requirements of ideal efficiencies and zero background. Very high efficiencies and low background are needed, but these requirements may be met in the future.