Systematic study of impact parameter dependent K-vacancy probabilities in near symmetric gas- and solid-target collision systems

K-vacancy production probabilitiesP _K (b) were measured with gas and solid targets byK-x-ray particle coincidences (impact parameterb is determined by the particle detection angle) in the region of light (Z _P ?Z _T ?10) up to intermediate heavy (Z _P ?Z _T ?36) collision systems. The measuredP _K (b) reveal a very strong difference in shape between solid and gas targets independent ofZ. Only theP _K (b) measured with gas targets and those measured with solid targets at very small impact parameters show reasonable good agreement with the 2pπ _x-2pσ rotational coupling model. At largeb theP _K (b) from solid targets are strongly influenced by a multiple collision effect, where projectileL-vacancies seem to be produced in collisions beforeK-vacancy production. However, this effect cannot be understood just by a two collision process whereL-vacancy production and 2pπ _x-2pσ rotational coupling occurs in consecutive collisions.     

Development of a high-pressure ion-exchange system for rapid preparative separations of trans-uranium elements

In the course of ion-exchange separations of highly active solutions, the radiolysis gives rise to considerable disturbances and deteriorated separation results. On the example of²⁴¹Am/²⁴²Cm separations some results of radiolysis investigations for Dowex 50X8 are briefly shown, and experiences with the choice of parameters of a high-pressure column system are described for several examples.     

Quality assurance in pesticide residue analysis

Summary During the last few years, the Working Group Pesticide Residues of the Food Chemistry and Forensic Chemistry Division of the Gesellschaft Deutscher Chemiker (German Chemical Society) has organised six laboratory performance tests on the analysis of pesticide residues in which numerous laboratories were involved. In these tests the choice of the analytical methods for the examination of fats or vegetable substrates was free. Organochlorine pesticides in concentrations of over 0.01 mg/kg were mostly readily identified, whereas in the analysis of organophosphorus residues often only the classic compounds (parathion, diazinon, etc.) were reported. Many a false positive result could have been avoided by using more adequate methods for confirmatory analysis. The quantitative results, however, were generally quite reliable and were mostly within the official acceptable dispersion range. It can be concluded that the performance of a residue laboratory is by no means constant, and that it is necessary to assess regularly the quality of the analytical results by participating in such interlaboratory tests.

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Qualitätssicherung bei Rückstandsanalysen von PflanzenschutzmittelnErfahrungen aus Ringversuchen

     

Die Konstitution der Michael-1,3-Addukte von Cyanessigsäureäthylester an konjugierte Systeme

Zusammenfassung Es wird gezeigt, daß bei der Einwirkung von Cyanessigester auf p-Benzochinon bzw. auf 2,4-Dimethyl-o-chinolacetat Verbindungen entstehen, denen auf Grund der IR-Spektren die Konstitution von Amino-benzofurancarbonsäure-estern zugeschrieben werden muß. Sowohl bei alkalischer als auch bei saurer Verseifung erfolgt Sprengung des Furanringes, intermediär entsteht ein Nitril, das sehr leicht weiter zur Säure bzw. einem Lacton verseift wird. Die Aminogruppe der genannten Aminobenzofuranderivate ist unter energischen Bedingungen zu einer Diacetylaminogruppe acetylierbar. Die Monoacetylverbindung tritt nur als schwer isolierbares Zwischenprodukt auf und ist besser unter milden Verseifungsbedingungen aus der Diacetylverbindung zugänglich. Die Aminogruppe ist unter üblichen Bedingungen nicht titrierbar; sie verhält sich in diesem Belang chemisch völlig anders als die des Anthranilsäureäthylesters, der titrierbar ist. Im IR-Spektrum zeigen hingegen Anthranilsäureäthylester und Aminobenzofuransäureäthylester sehr große Ähnlichkeiten. Eine Erklärung dieser Diskrepanzen hinsichtlich des chemischen Verhaltens und der spektralen Eigenschaften kann derzeit nicht gegeben werden.Mit 1 Abbildung     

Die Charaktere der symmetrischen Gruppe

Ohne ZusammenfassungHerrnOskar Perron zum 80. Geburtstag am7. Mai 1960     

Enhanced photoactivity of antimony phosphates by substitution of H+, Cu2+ and N3− in the K3Sb3P2O14·xH2O crystal lattice

Research on Chemical Intermediates - Substitutional doping of framework heteroatoms in photocatalysis is one of the approaches for harvesting visible light. Tunnel structure potassium antimony...     

φ production in In–In collisions at 158 A GeV

The NA60 experiment has measured muon pair production in In–In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of φ→μ μ meson production. Differential spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity distribution is found to be constant as a function of centrality, compatible with previous results. The decay muon polar angle distribution is measured in several reference frames. No evidence of polarization is found as a function of transverse momentum and centrality. The analysis of the p _T spectra shows that the φ has a small radial flow, implying a weak coupling to the medium. The T _eff parameter measured in In–In collisions suggests that the high value observed in Pb–Pb in the kaon channel is difficult to reconcile with radial flow alone. The absolute yield is compared to results in Pb–Pb collisions: though significantly smaller than measured by NA50 in the muon channel, it is found to exceed the NA49 and CERES data in the kaon channel at any centrality. The mass and width are found to be compatible with the PDG values at any centrality and at any p _T : no evidence for in-medium modifications is observed.     

Direct determination of polycyclic aromatic hydrocarbons in solid matrices using laser desorption/laser photoionization ion trap mass spectrometry

The development and characterization of a new instrument for solid sampling which couples IR laser desorption followed by UV laser photo-ionization and analysis using an ion trap mass spectrometer has been investigated. For calibration, a new type of solid sample preparation involving activated charcoal as the solid substrate was used. This solid sample provided a steady signal for several thousand laser shots, which allowed optimization of the experimental procedure. It was found that both the IR and UV intensity and the delay between them play an important role in both the magnitude and type of signals observed. A method of gas phase accumulation with multiple laser shots was examined. Finally, this technique was demonstrated to be effective in providing direct qualitative information for N.I.S.T. SRM 1944 river sediment sample with no sample pre-treatment.