锂盐阴离子和不同侧基的15-冠-5系冠醚对锂盐/冠醚固态配合物远红外位移的影响

按文献的方法研究了锂盐阴离子和不同侧基的15-冠-5系冠醚对四种锂盐/冠醚固态配合物远红外位移的影响.     

From direct to absolute mass measurements: A study of the accuracy of ISOLTRAP

For a detailed study of the accuracy of the Penning trap mass spectrometer ISOLTRAP all expected sources of uncertainty were investigated with respect to their contributions to the uncertainty of the final result. In the course of these investigations, cross-reference measurements with singly charged carbon clusters ¹²C⁺ _n were carried out. The carbon cluster ions were produced by use of laser-induced desorption, fragmentation, and ionization of C₆₀ fullerenes and injected into and stored in the Penning trap system. The comparison of the cyclotron frequencies of different carbon clusters has provided detailed insight into the residual systematic uncertainty of ISOLTRAP and yielded a value of 8×10^-9. This also represents the current limit of mass accuracy of the apparatus. Since the unified atomic mass unit is defined as 1/12 of the mass of the ¹²C atom, it will be possible to carry out absolute mass measurements with ISOLTRAP in the future. Received 7 June 2002 Published online 6 November 2002 RID="a" ID="a"e-mail: a.kellerbauer@cern.ch RID="b" ID="b"Current address: Centre de Physique des Particules de Marseille, 13288 Marseille Cedex 9, France.     

Multi-band spectra of odd and even nuclei of the s-d shell

The energy levels of^{21, 23}Na,^{22, 23}Ne,^{24, 28}Mg and^{25, 29}Al are obtained by mixing various bands using the projected deformed Hartree-Fock (DHF) method. Solutions having minimum energies are found to be prolate for all the nuclei considered here. Higher bands are obtained either by considering particle-hole excitations or oblate solutions. These various bands are mixed using the projection method and care has been taken to orthogonalize the bands. The interactions used in this study are those given by Kuo, Preedom-Wildenthal (PW) and WHMK interactions. The last one seems to give good results for most of the nuclei considered here. Not only are the lowest bands well-reproduced but the second lowest bands agree reasonably well in most nuclei. The third lowest ones obtained in some nuclei are not yet observed as complete bands. However, K obtained for the third band seems to be correct. A comparison with shell model calculations—which are numerically exhausting—shows similar results for the lowest band. However, the agreement of the second band varies from nucleus to nucleus. A comparison between matrix elements of the interactions is made to analyze the results.     

A flexible approach for the synthesis of selectively labelled l-arginine

A simple and efficient synthesis of l-arginine has been achieved in 12 steps and 24% overall yield. Regioselective reduction and functional group manipulation of the β-side chain of aspartic acid allowed the preparation of an ornithine derivative, which was then guanylated with a bis-protected 1-guanyl-pyrazole and deprotected to give l-arginine. This approach allows the flexible incorporation of stable isotopes and this is demonstrated using potassium ¹³C-cyanide, which has resulted in the preparation of 5-¹³C-l-arginine.     

Radiative and non-Radiative Fusion in Muonic Molecules

Considerable efforts in μCF studies (since [1]) were aimed at observation of various fusion processes. The impact of these studies on the understanding of properties of the lightest nuclei, the dynamics of low-energy fusion reactions and the Coulomb three-body system structure are reviewed. Unsolved theoretical and experimental problems are summarized. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Particles in Classically Forbidden Area for Exotic Nuclei in Ca Isotopes

Particles in classically forbidden area were studied with the Skyrme-Hartree-Fock theory for Ca isotopes from β stability line to neutron drip line. The number of neutrons in the classically forbidden area increases with mass number A, because of the increase of the number of neutrons occupied in the weakly-bound open shell. The number of protons in the classically forbidden area, in contrast, decreases with mass number A, because the orbits of protons become more tightly bound. It is shown that the number of particles in the classically forbidden area can give information on the appearance of the halo or skin.     

Studies on Trace Labelling of Bromsulphalein (BSP) with Radioiodine

Two methods have been studied for high specific activity trace iodination of Bromsulphalein (BSP) with radioiodine (¹³¹I). In the first method, BSP in aqueous solution is reacted with iodine and an oxidising agent – hydrogen peroxide or chloramine T. In the second method, iodination is carried out by electrolytically liberated iodine. The electrolytic method gives labelled BSP free from any labelled degradation products. The stability of ¹³¹I-labelled BSP in aqueous solution has been studied. The product has been found to remain more stable in aqueous solutions at a slightly acid pH (4…6.5) than in dilute alkaline solutions (pH 7…9.5).     

Über Modelle in der Geochemie der Isotope

Bei der Vertiefung unseres Verständnisses der Gesetzmäßigkeiten der Verbreitung stubiler und radioaktiver Isotope in der Natur spielen Modelle eine wachsende Rolle. Anhand eines allgemeinen Modells des Kreislaufs chemischer Elemente und ihrer Isotope in der Natur werden die Eigenschaften konkreter, globaler wie regionaler Modelle der Geochemie der Isotope abgeleitet. Es wird auf die Rolle globaler Modelle sowie auf das Verhāltnis globaler und regionaler Modelle zueinander eingegangen. Durch die Einführung eines Parameters, der die Geschwindigkeit des Stoff- und Isotopenaustauschs einer Region mit den globalen Vorrāten beschreibt, können globule und regionale Modelle der Geochemie der Isotope miteinander verbunden werden.