[en] Humic and fulvic acid can be combined under the term 'humic substances' and are natural substances with a complex structure. The structural details are not known, however, due to the functional groups present in these compounds the formation of hydrogen bonds is easily attained. Several humic substances were investigated for their potential use as compounds, which are applicable for tritium enrichment from aqueous solution. For comparison a simple compound, malonic acid, representing only few functional groups was investigated. The experiments were performed using a cryosublimation apparatus, which was run well below equilibrium vapor pressure to avoid any isotope fractionation of HTO and H₂O. A higher enrichment factor was found for natural humic acid compared to fulvic acid, however, no enrichment could be found for a synthetic humic acid and malonic acid. Interpretation of the results is difficult since no detailed information on the chemical structure of humic substances is known

[en] With the recent synthesis of superheavy nuclides produced in the reactions ⁴⁸Ca+²³⁸U and ⁴⁸Ca+^242,244Pu, much longer-lived nuclei than the previously known neutron-deficient isotopes of the heaviest elements have been identified. Half-lives of several hours and up to several years have been predicted for the longest-lived isotopes of these elements. Thus, the sensitivity of radiochemical separation techniques may present a viable alternative to physical separator systems for the discovery of some of the predicted longer-lived heavy and superheavy nuclides. The advantages of chemical separator systems in comparison to kinematic separators lie in the possibility of using thick targets, high beam intensities spread over larger target areas and in providing access to nuclides emitted under large angles and low velocities. Thus, chemical separator systems are ideally suited to study also transfer and (HI, αxn) reaction products. In the following, a study of (HI, αxn) reactions will be presented and prospects to chemically identify heavy and superheavy elements discussed

[en] The decomposition behavior of group 6 metal hexacarbonyl complexes (M(CO)_6) in a tubular flow reactor is simulated. A microscopic Monte-Carlo based model is presented for assessing the first bond dissociation enthalpy of M(CO)_6 complexes. The suggested approach superimposes a microscopic model of gas adsorption chromatography with a first-order heterogeneous decomposition model. The experimental data on the decomposition of Mo(CO)_6 and W(CO)_6 are successfully simulated by introducing available thermodynamic data. Thermodynamic data predicted by relativistic density functional theory is used in our model to deduce the most probable experimental behavior of the corresponding Sg carbonyl complex. Thus, the design of a chemical experiment with Sg(CO)_6 is suggested, which is sensitive to benchmark our theoretical understanding of the bond stability in carbonyl compounds of the heaviest elements.

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[en] The concentrations of the long-lived nuclear reaction products "1"2"9I and "3"6Cl have been measured in samples from the MEGAPIE liquid metal spallation target. Samples from the bulk target material (lead-bismuth eutectic, LBE), from the interface of the metal free surface with the cover gas, from LBE/steel interfaces and from noble metal absorber foils installed in the cover gas system were analysed using Accelerator Mass Spectrometry at the Laboratory of Ion beam Physics at ETH Zuerich. The major part of "1"2"9I and "3"6Cl was found accumulated on the interfaces, particularly at the interface of LBE and the steel walls of the target container, while bulk LBE samples contain only a minor fraction of these nuclides. Both nuclides were also detected on the absorber foils to a certain extent (<< 1% of the total amount). The latter number is negligible concerning the radio-hazard of the irradiated target material; however it indicates a certain affinity of the absorber foils for halogens, thus proving the principle of using noble metal foils for catching these volatile radionuclides. The total amounts of "1"2"9I and "3"6Cl in the target were estimated from the analytical data by averaging within the different groups of samples and summing up these averages over the total target. This estimation could account for about half of the amount of "1"2"9I and "3"6Cl predicted to be produced using nuclear physics modelling codes for both nuclides. The significance of the results and the associated uncertainties are discussed.

[en] Dinitrogen pentoxide has aroused significant interest in atmospheric chemistry because of its importance in the night time chemistry of nitrogen oxides to influence the tropospheric oxidation capacity. We have used an established method of ¹³N production to synthesize ¹³N labeled N₂O₅ for the first time in order to study N₂O₅ uptake kinetics on aerosol particles. ¹³N is produced via the ¹⁶O(p,α)¹³N reaction in a gas target attached to the IP2 endstation of the Injector 2 cyclotron at PSI. The ¹³NO produced in the gas target is transported to a laboratory where it is mixed, under dry conditions, with non-labeled NO and O₃ in a gas reactor, giving ¹³NNO₅. The N₂O₅ thus produced is fed into an aerosol flow tube together with a humidified aerosol gas flow. The gaseous species present in the resulting gas flow are selectively separated via a narrow parallel plate diffusion denuder system, while aerosol particles can be trapped on a particle filter placed at the end of the denuder system. The activity of the ¹³N labeled species trapped on the denuder plates and in the particle filter can be monitored via scintillation counters. A system for the routine online production of ¹³N labeled N₂O₅ has been assembled and used to assess the conformity of the results by kinetic modeling of gas phase N₂O₅ chemistry, showing good agreement. A few exemplary experiments of uptake of labelled N₂O₅ to ammonium sulfate and citric acid particles are presented that are in good agreement with results obtained with other methods reported in the literature.

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[en] At the new research reactor FRM II in Garching near Munich the beam guide with the highest cold neutron flux is dedicated to Prompt Gamma-ray Activation Analysis (PGAA) and related neutron capture experiments. We have designed a partially ballistic form of the neutron guide with the aim of concentrating the cold neutrons at the target position of the PGAA experiment. The cold neutron flux with a mean energy of only 1.83 meV was measured about 10.5 cm far from the second exit window and reached intensity of 1.7x10¹⁰ n/cm² s at a 2 mmx2 mm gold foil. The PGAA installation is now prepared for three different kinds of measurements--standard PGAA, Neutron Tomography of small samples and position sensitive PGAA, or PGAI for short. We have also measured γγ coincidences in ⁷⁷Ge. In this paper, we want to introduce the PGAA facility, show the diversity of the recently performed experiments and discuss further possibilities.

[en] At the research reactor Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) a new Prompt Gamma-ray Activation Analysis (PGAA) facility was installed. The instrument was originally built and operating at the spallation source at the Paul Scherrer Institute in Switzerland. After a careful re-design in 2004-2006, the new PGAA instrument was ready for operation at FRM II. In this paper the main characteristics and the current operation conditions of the facility are described. The neutron flux at the sample position can reach up 6.07x10¹⁰ [cm^-2 s^-1], thus the optimisation of some parameters, e.g. the beam background, was necessary in order to achieve a satisfactory analytical sensitivity for routine measurements. Once the optimal conditions were reached, detection limits and sensitivities for some elements, like for example H, B, C, Si, or Pb, were calculated and compared with other PGAA facilities. A standard reference material was also measured in order to show the reliability of the analysis under different conditions at this instrument.