A PC-Program for the Calculation of Neutron Flux and Element Contents Using the ki-Method of Neutron Activation Analysis

A computer program is described, which calculates the induced activities of isotopes after irradiation in a known neutron field, thermal and epithermal neutron fluxes from the measured induced activities and from nuclear data of 2–4 monitor nuclides as well as the element concentrations in samples irradiated together with the monitors. The program was developed for operation in Windows 3.1 (or higher). The application of the program for neutron activation analysis allows to simplify the experimental procedure and to reduce the time. The program was tested by measuring different types of standard reference materials at the FRJ-2 (Research Centre, Jülich, Germany) and Triga (University Mainz, Germany) reactors. Comparison of neutron flux parameters calculated by this program with those calculated by a VAX program developed at the Research Centre, Jülich was done. The results of testing seem to be satisfactory.     

Determination of characteristic neutron flux parameters of nuclear reactors for thermal neutron activation analysis

The characteristic neutron spectrum parameters for thermal neutron activation analysis have been determined for the most important irradiation positions of the reactors BR1 and BR2 at Mol (Belgium), HFR at Petten (Netherlands) and FRJ2 at Jülich (Federal Republic of Germany). The method of determination is described.     

Trace analysis by intermediate trapping with a modified programmable temperature vaporizer

Summary A system for quantitative transfer of thermally desorbed substances onto capillary columns is described. During desorption substances are intermediately trapped in a programmable temperature vaporizer (PTV) cooled to –150°C. After condensation the injector is heated to a preset temeprature in a few seconds. Various applications are mentioned.Extract from planned Thesis of E. Jülich with authorization of the Faculty     

Electrometric determination of the pH of atmospheric precipitation

Summary Reliable pH-determination of rain water represents a difficult task both from the theoretical and practical point of view because the chemical composition and conductivity of rain water samples varies widely. The method for determining the pH is described that was used during our systematic study of the acidity of rain in various regions of the FRG from 1980 to 1985 and the problems encountered are discussed. Potential sources of error are inadequate sampling, sample storage, and electrometrical pH-determination of samples with a very low conductivity. The use of various types of electrodes, their pretreatment, storage and time response as well as the accuracy of the determination are discussed. Examples are given of the application of the method for determining the time dependence of the pH during single rain events in Jülich as well as average monthly pH-values in polluted and nonpolluted regions in the Federal Republic of Germany.

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Elektrometrische Bestimmung des pH-Wertes von atmosphärischen Niederschlägen

Zusammenfassung Eine zuverlässige Bestimmung des pH-Wertes des Regenwassers ist wegen unterschiedlicher Zusammensetzung und Leitfähigkeit des Regenwassers verschiedener Herkunft mit theoretischen und praktischen Problemen verbunden. Die während einer langzeitigen Meßreihe des pH-Wertes in verschiedenen Regionen der Bundesrepublik in den Jahren 1980–85 angewendete Methode wird beschrieben und die dabei auftretenden Probleme der pH-Bestimmung diskutiert. Die mangelhafte Richtigkeit ist vor allem auf die Probennahme, Probenlagerung und elektrometrische Bestimmung des pH-Wertes bei einer geringen Leitfähigkeit der Probe zurückzuführen. Verwendung verschiedener Elektrodentypen, ihre Vorbehandlung, Lagerung, Einstellungszeit und Genauigkeitsgrenzen des Meßwertes werden erörtert. Als Beispiel der Verwendung der Meßmethode werden Resultate aus der pH- und Leitfähigkeitsbestimmung in einzelnen Regenvorgängen in Jülich und in durchschnittlichen Monatsproben aus verschiedenen belasteten und nicht belasteten Regionen der Bundesrepublik angeführt.

     

Ionic space charge phenomena during SIMS analysis of ceramic materials

Summary Despite recent progress in instrument design the surface analysis of poorly conducting materials by modern techniques operating with either primary and/or secondary charged particles always leads to an accumulation of electric charges on the bombarded surface. In materials with an appreciable ionic conductivity the resultant electric field will induce the migration of mobile species and will therefore modify elemental concentration profiles. As an illustration of this problem we present a phenomenological study of an ionic model material which contains only one mobile species (e.g. sodium or hydrogen in oxide glasses at room temperature). A simultaneous numerical solution of the diffusion equation and of Poisson's equation permits to calculate the electric field and the ionic charge carrier concentration profiles in the near surface region of the material as a function of time. Although material ablation by sputtering is not yet taken into account, this approach gives useful insights into what happens in the near surface region of an ionic conductor on analysing it by SIMS or related techniques which also produce shallow charged layers on the surface of the target. On the other hand, the results are also applicable to plasma based treatments of glass surfaces currently applied in PVD coating processes.Presented at the 7th Working Conference on Applied Surface Analysis at Jülich (Germany), June 22–25, 1992 [Other lectures and posters in Fresenius' J Anal Chem (1993): 346:1–3]     

Direct solid vs. slurry analysis of tobacco leaves for some trace metals by graphite furnace AAS

Summary Graphite furnace atomic absorption spectrometry (GFAAS) is used to determine cadmium, lead, nickel and cobalt in two samples of tobacco leaves (candidate reference materials). Two techniques for the direct determination of these elements are investigated — direct solid sampling into a ring chamber tube specially designed for the Zeiss AAS-3 spectrometer and slurry sampling. For both investigated sampling methods the optimum parameters of temperature-time programs, influence of Pd modifier and calibration methods are discussed. There is acceptable agreement between the results obtained from direct solid, slurry and solution (after wet decomposition) sampling.Presented at the 4th International Colloquium on Solid Sampling with Atomic Spectroscopy, October 8–10, 1990; Jülich, Federal Republic of Germany     

The single-comparator method in thermal neutron activation analysis extended for some (n,p) reactions

From experimental studies of the rate of the reactions⁴⁷Ti(n, p)⁴⁷Sc,⁴⁸Ti(n, p)⁴⁸Sc and⁵⁸Ni(n, p)⁵⁸Co in four nuclear reactors, it is concluded that for the irradiation positions of the light water moderated reactors BR2 (Mol, Belgium) and HFR (Petten, Netherlands) a simple empirical relation exists between the fast neutron flux on the one hand and the thermal and epithermal neutron flux on the other. The graphite moderated reactor BR1 (Mol, Belgium) and the heavy water reactor FRJ2 (Jülich, Federal Republic of Germany), however, have relatively much lower fast fluxes and their irradiation facilities do not obey the empirical relation determined.     

Direct determination of atmospheric lead by Zeeman solid sampling graphite furnace atomic absorption spectrometry (GFAAS)

Summary Atmospheric lead was collected by membrane filters using two low volume air samplers at Jülich, Stolberg, and Wetzlar, Federal Republic of Germany. Sampling times varied from 2 to 8 h. After sampling, each filter was subsampled in two cross-sections using a clean stainless steel punch (diameter 5 mm). The lead content of each subsample disc was determined directly by Zeeman GFAAS, calibrated with aqueous standard solutions and supported by solid reference materials. The distribution of lead between the subsamples was generally homogeneous, with standard deviations ranging from 11 to 37%, but typically <15% for samples with 8 h sampling time. The analysis of each filter usually took about 30 min. The differences in air quality between the three sampling locations, as measured by the lead concentrations, are discussed. In general, Stolberg appears to have the highest lead concentrations. The mass particle-size distribution of lead in the aerosol samples collected by membrane filters using a cascade impactor at Stolberg was also investigated with the same analytical technique. Using graphite platform boats as direct samplers, it is possible for the dry deposition flux of lead to be estimated. This provides a quick means of assessing the levels of lead pollution in the atmospheric environment. With lead concentrations measured in parallel, the dry deposition velocities of lead can be estimated under various meteorological conditions. Application of similar sampling and analytical techniques to other atmospheric trace metals may be possible.     

Quantitative electron probe microanalysis for the characterization of thin carbon-boron layers in fusion devices

Summary The first wall of the fusion device TEXTOR at the Forschungszentrum Jülich has been coated in situ with an amorphous hydrogen rich carbon/boron film (a-C/B:H) which reduces plasma impurities caused by the plasma surface interaction. The results of the coating process of the 35 m² large inner wall surface have been controlled by a recently developed modification of the quantitative electron probe microanalysis, which has been applied to 12 samples from specified positions inside the tokamak. The quantification itself is based on a Monte Carlo simulation of electron trajectories providing very accurate results for X-ray intensities emitted by elements present in the electron bombarded sample. The Monte Carlo results are used in the present work to calibrate the measured X-ray intensities emitted by boron and carbon from the a-C/B:H layers deposited on pure silicon substrates. As a result the total deposited mass of the layer per area unit as well as the composition of the layers (except hydrogen) could be determined very accurately. The relative errors were less than 7%. The limit of detectability were found to be in the range of one monolayer for boron as well as for carbon.     

Polarography of piazothiol and piazoselenol in aqueous solutions

Summary The polarographic reduction of piazothiol and piazoselenol, like that of benzofurazan, studied earlier, involves the participation of 6 electrons and the formation of ortho-phenylenediamine. The transfer of the first electron is preceded by a reversible protonation of the molecules. Hydrogen selenide formed in the reduction of piazoselenol gives the anodic wave of mercury ionization. Reducibility increases in the series: benzofurazan, piazothiol, piazoselenol in contrast to the increase in electronegativity of the key heteroatoms Se, S, O.

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Zusammenfassung Bei der polarographischen Reduktion von Piazothiol und Piazoselenol sowie von Benzofurazan findet ein Übergang von 6 Elektronen statt, wobei o-Phenylendiamin gebildet wird. Dem Übergang des ersten Elektrons geht eine reversible Protonisierung des Moleküls voraus. Selenwasserstoff, der bei der Reduktion von Piazoselenol entsteht, verursacht die anodische Stufe der Quecksilber-Ionisierung. Die Reduzierbarkeit steigt in der Reihenfolge Benzofurazan-Piazothiol-Piazoselenol an, im Gegensatz zu den zunehmenden elektronegativen Eigenschaften der Heteroatome Se-S-O.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.

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Die Redaktion wurde bei der Herausgabe und wissenschaftlichen Bearbeitung dieses Heftes von Herrn Dr. H. W. Nürnberg, Kernforschungsanstalt Jülich, wesentlich unterstützt.     

Eine Meßapparatur zur Untersuchung des Kriech- und Relaxationsverhaltens von Polymeren unter Torsion

Zusammenfassung Zur experimentellen Bestimmung der Kriechfunktion J(t) und der Relaxationsfunktion G(t) unter Torsionsbelastung der Probe wurde eine Meßapparatur entwickelt. Das mechanisch-elektrische Meßprinzip sowie eine Prozeßrechnerkopplung gestatten einen weitgehend automatischen Meßbetrieb. Änderungen an den physikalischen Versuchsbedingungen können rein Software-seitig durchgeführt werden.Das entsprechende Auswerteprogramm liefert neben numerischen Werten eine Zeichnung der entsprechenden Masterkurven, die mit Hilfe der WLF-Gleichung konstruiert werden.Messungen an kommerziellem PMMA zeigen einen Meßz bereich fürJ(t) von 10^–9 bis 10^–5 m²/N und für G(t) von 10° bis N 10⁵ N/m² ; das zugängliche Temperaturintervall liegt zwischen –180 °C und 200 °C. Damit ist der für die meisten Polymere erforderliche Bereich erfaßt.Mit 9 Abbildungenjetzt: KFA Jülich GmbH, Institut für Festkörperforschung (IFF).     

In situ ion implantation for quantification in secondary-ion mass spectrometry

Summary The primary ion beam column of a secondary ion mass spectrometer has been used to produce an internal quantification standard via in situ ion implantation. Subsequent depth profile analysis has been done in the instrument after switching to another primary projectile. In this way, the interfacial oxygen concentration between an amorphous and crystalline Si layer and the hydrogen content ( 30 at %) in a 48 nm amorphous carbon layer on a silicon substrate have been determined. The use, in the latter case, of deuterium as an in situ implant exemplifies that minor isotopes can be employed for the quantification in secondary-ion mass spectrometry of components with high concentrations while achieving an accuracy of better than ±50%

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In-situ-Ionenimplantation für quantitative Bestimmungen in der Sekundärionen-Massenspektrometrie

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Work performed at Institut für Grenzflächenforschung und Vakuumphysik, Kernforschungsanlage Jülich     

Epoxy-POSS/silicone rubber nanocomposites with excellent thermal stability and radiation resistance

Due to the rigid Si-O-Si backbone, silicone rubber (SR) have a widespread application in extreme environment such as high temperature and high-level radiation. However, the radiation stability of SR still does not meet the practical needs in special radiation environments. Herein we prepared epoxy POSS(ePOSS)/SR nanocomposites with excellent thermal stability and radiation resistance. As a physical crosslinking point in the SR, addition of small amount of ePOSS not only enhanced the mechanical properties of the matrix, but also improved its thermal stability greatly due to their good compatibility. ePOSS/SR had higher radiation stability in air than SR owing to the inhibition of radiation oxidation by ePOSS, and the yield of main gaseous radiolysis products (CH₄, H₂, CO and CO₂) of SR and ePOSS/SR nanocomposites was determined. By analyzing the changes of chemical structure, thermal properties and mechanical properties of the ePOSS/SR nanocomposite, combined with the characteristics of gas products after γ-irradiation, the radiation induced crosslinking and degradation mechanism of the nanocomposites was proposed comprehensively.     

Zum Mechanismus der Extraktion von Tellur (IV) aus salzsaurem Medium mit ges?ttigten aliphatischen Monoketonen

Zusammenfassung Die Untersuchung erstreckte sich auf die Extraktionsmittel Methyläthylketon, Methylisopropylketon, Methylisobutylketon und Diisobutylketon. Im besonders eingehend untersuchten Solvens Methylisobutylketon wird für die extrahierbare Verbindung die Formel H₂Te(OH)₂Cl₄ · Ket₅(H₂O)_4–8 vorgeschlagen. Die beiden durch Dissoziation dieser Säure gebildeten Wasserstoffionen sind in ihrer primären Solvathülle hydratisiert und die Hydratwassermoleküle werden durch Ketonmoleküle über Wasserstoff brücken außerdem sekundär solvatisiert. Das Anion [Te(OH)₂Cl₄]^2– ist wahrscheinlich durch -OH-O=C-Bindungen durch Keton solvatisiert.Wir danken dem Bundesministerium für Bildung und Wissenschaft, Bonn, sowie der IAEA, Wien, für die Ermöglichung dieser Arbeit, den Herren Dr. G. Erdtmann, Dipl.-Phys. H. Petri und Dipl.-Ing. M. Rauschen, Zentralinstitut für Analytische Chemie der Kernforschungsanlage Jülich GmbH, für ihre Unterstützung bei radiochemischen und meßtechnischen Fragen, sowie Herrn Dr. W. Krasser vom gleiehen Institut für die ramanspektroskopischen Untersuchungen.     

Trennung der Lanthaniden mittels Niederdruck-S?ulen-Chromatographie

Zusammenfassung Mit dem Laufmittel Diethylether/ bis-(2-ethylhexyl)-phosphat (HDEHP)/Tetrahydrofuran (THF)/Salpetersäure [1000,5(1 M)33] können mittels Niederdruck-Säulen-Chromatographie alle Lanthaniden getrennt werden. Die Retentionszeiten sind stark von der Konzentration der aktiven Laufmittel HDEHP und THF abhängig; dasselbe gilt für den Wassergehalt. Kieselgel erwies sich als das beste Trägermaterial. Der Trennmechanismus der einzelnen Lanthaniden beruht auf einer Verteilungsreaktion beim säulen-chromatographischen Transport.Wir danken der Firma Bayer AG für Chemikalien (HDEHP), Herrn Dr. Rottmann und Herrn Schmitz von der KFA Jülich für die stets hilfreiche Unterstützung zur Herstellung aktiver Lanthaniden.     

Collection, preparation and characterization of fresh, marine candidate reference materials of the German Environmental Specimen Bank

Summary The Environmental Specimen Bank (ESB) of the Federal Republic of Germany has been collecting and preparing specially selected biological reference materials since 1982 to help to control representative ecosystems. The preparation and homogenization of the sample material is carried out at cryogenic temperatures, below minus 150°C. There is a broad palette of fresh candidate RMs, stored at the ESB Jülich, characterized not only for special trace elements and essential bulk elements but also for polycyclic aromatic hydrocarbons (PAH) and chlorinated hydrocarbons (CHC). Just for organic analysis there is a need of fresh RMs, which can be filled by the ESB reference materials.     

Aspects of cleaning environmental materials for multi-element analysis, e.g. plant samples

Summary Cleaning of samples is often the first step in the entire procedure of sample preparation in environmental trace element research. The question must generally be raised of whether cleaning is meaningful before chemical investigations with plant material (e.g. for the determination of transfer factors in the soil/plant system) or not (e.g. for food chain analysis in the plant/animal system). The most varied cleaning procedures for plant samples are currently available ranging from dry and wet wiping of the leaf or needle surface up to the complete removal of the cuticule with the aid of chloroform. There is at present no standardized cleaning procedure for plant samples so that it is frequently not possible to compare analytical data from different working groups studying the same plant species.Modified paper presented at the IAEA training course on Sampling, sample preparation and data evaluation for multielement and radionuclide analysis by nuclear and instrumental methods from November 6th to December 1st 1989 at the Research Centre in Jülich, FRG     

Beitrag zur Charakterisierung von hochborhältigen Chrom-Nickel-Molybdän-Kupfer-Stählen mit Hilfe der stereometrischen Analyse

Zusammenfassung Eine Serie von Chrom-Nickel-Molybdän-Kupfer-Bor-Stählen mit Borgehalten von 0,5 bis 1,9 Gew.% wurde mit Methoden der stereometrischen Analyse untersucht. Mit verschiedenen Verfahren der Phasenanalyse wurden Informationen über die Verteilung der Elemente und die chemische Zusammensetzung der Phasen dieser Werkstoffe gewonnen. Diese Informationen dienten als Ausgangspunkt für die Strukturanalyse der Boridphase, in deren Rahmen in erster Linie die Frage des Einflusses der chemischen Zusammensetzung auf die Größe der Elementarzelle und damit die Dichte der Boridphase untersucht wurde. Die Werkstoffserie wurde schließlich gefügeanalytisch charakterisiert, wobei die Technik der automatischen Linearanalyse mit der Mikrosonde und die chemische Isolierung der Boride mit lichtoptischer Untersuchung des Isolates angewendet und beispielhaft gegenübergestellt wurden. Die mit den Methoden der Struktur-, Phasen- und Gefügeanalyse gewonnenen Informationen wurden schließlich in einer Bilanz verknüpft.

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On the characterization of Cr-Ni-Mo-Cu-B-alloys by means of stereometric analysis

Summary A series of Chromium-Nickel-Molybdenum-Copper-Boron steel with Boron concentrations in the range from 0,5–1,9 wt.% has been investigated with the methods of stereometric analysis. Different techniques of phase analysis are used to gain information about the distribution of the different elements and the composition of the phases. These informations are the basis for structure analysis of the boride phase. Within this chapter mainly the influence of chemical composition of the boride on the lattice parameters and consequently on the density of the phase are investigated. Furthermore this series of steel is investigated with different methods of quantitative metallography (automatic linear analysis with an electron microprobe and chemical isolation of the boride phase with subsequent light microscopical investigation). The results obtained with the two techniques are compared for one sample. Finally the informations obtained with structure analysis, phase analysis and quantitative metallography are combined to form a balance of stereometric analysis.