Die aktivierungsanalytische Bestimmung von Verunreinigungen in Uranverbindungen nach papier-chromatographischer Abtrennung des Urans

Ohne Zusammenfassung     

The Conformation of 1,6-Diaza-2,7-cyclodecadione in Solution

From ¹H- and ¹³C-NMR. data, a crown conformation with trans amide bonds is deduced for 1,6-diaza-2,7-cyclodecadione ( 1 ) in solution. Compound 1 was obtained by reaction of 2-pyrrolidone with POCl₃.     

Stoßbestimmte Relaxation des Elektronenensembles im Plasma bei zusätzlicher Aufheizung durch ein elektrisches Feld. III. Das periodische Verhalten der Elektronenkomponente im elektrischen Feld großen Modulationsgrades

Collision Dominated Relaxation of the Electron Ensemble in a Plasma with Additional Heating by an Electric Field. III. The Periodic Behaviour of the Electron Component in an Electric Field with a Large Modulation Amplitude With the aid of the non-stationary Boltzmann-equation the periodic behaviour of the isotropic part of the velocity distribution of electrons and thereby determined macroscopic quantities is calculated for periodic electric fields with large modulation amplitude. The investigations concern a weakly ionized column plasma in neon under typical low and medium pressure conditions. Based on the numerical results for typical ranges of field strength and cycle times of the electric field a qualitative physical interpretation for the periodic behaviour of the electron component is obtained. The introduction of special field-dependent adjustment times allows the formalution of conditions which characterize the case of quasi-stationary behaviour and also the case of small amplitudes of modulation in the macroscopic quantities determined by the isotropic distribution function. The periodic states between these two limiting cases can be interpreted as due to two competing processes. The first one is the energy input controlled by the electric field and the second one is the energy loss in binary collisions of the electrons with the atoms.     

Analyse von Hyperfeinstrukturen des Eu151, Am241 und einiger 3 d-Elemente mittels „Exchange Polarization“

It is shown how several discrepancies in the optical hfs of the Eu can be understood as consequences of the exchange polarization of the inner and outers-electrons by the spin of the half filled (4f ⁷)-subshell, an effect which should produce additional magnetic fields at the nucleus. Thus from the two different values of the electronic splitting constanta _6s in the two Eu-II ground states the polarization field from the 6s-shell (Δ H _6s ) is determined to be ca. +260 KG, and the formal splitting constantσ (??3 mK) of the (4f ⁷)-subshell yields ca. ?350 KG for the fieldΔ H _(1?5) from the five innern s-shells (n=1?5) in good agreement with the strength of the inner field obtained from recent Mössbauer effect studies.Δ H _(1?5) is deduced to be approximately equal in all sufficiently analysed ground and excited configurations of the neutral and ionised Eu atom ((4f ⁷) 6s, 6p, 5d, 6s ² and 6s 6p). Other elements with half filled subshells (Am, Mn) show similar features in their optical hfs. For Am⁺ ((5f ⁷) 7s) ca. ?2200 KG are found for the inner field (Δ H _(1?6)). For several 3d-elements it was found that the agreement between the calculated polarization fields and those following from experimental results is better than assumed so far.     

Einen spezifischen Zinktest

Ohne Zusammenfassung     

Electric and magnetic hyperfinestructure investigations in the 5s 25p 3 and 5s 25p 26s Configurations of121, 123Sb

Optical hyperfinestructure investigations in several spectral lines were carried out in the Sb-I spectrum from which for the first time accurate values of the hfs-splitting constantsA andB of the ground configuration 5p ³ and also for five of the eight levels of the first excited configuration 5p ²6s were obtained. With these parameters the influence of core polarization effects is calculated to bea _c= ?6.6(4) mK, (equivalent to a magnetic field of ?283(20) kG perp-electron spin). The quadrupole momentQ ₁₂₁= ?0.36(4) b (including Sternheimer correction) was obtained with the experimental valuesb _3/2= ?14.3(1.0) mK and 〈r ^?3〉 =11.2(3) a.u. andQ ₁₂₃= ?0.49(5) b withb _3/2= ?19.9(1.0) mK resp. This evaluation also yields the relativistic correction factor η= ?(C″/C′) · S _r/R′ _r=1.13(2). —For the first time, too, isotope shift investigations in Sb-I lines were possible which permit to determine the isotope shift constant βC _exp= 40(10) mK, and a value δ〈r ²〉^{121, 123}=0.12(4) fm² for the change in the mean square nuclear charge radius between¹²¹Sb and¹²³Sb which is about 50 percent of the prediction of the unified nuclear model.     

Selective synthesis of the C3v isomer of C60h18

[chemical structure: see text]. C60H18 has been produced by hydrogenation of C60 at 100 bar H2 pressure and 673 K for 10 h. We have investigated the crude material without any purification by use of 1H NMR, 13C NMR, and IR spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. We show that the crude material consists of 95% of the C3v isomer of C60H18.     

Molybdenum phosphide as an o-propylaniline hydrodenitrogenation catalyst: a first principles study

MoP has been shown experimentally to be an active catalyst in the hydrodenitrogenation of o-propylaniline. We investigate the structure and the energetics of the o-propylaniline adsorption on the Mo-terminated MoP(001) surface. Detailed information on the structure of the free MoP(001) surface and on the structure and adsorption energy of o-propylaniline on MoP(001) is obtained by using density functional theory. The transition state, reaction path, and the energy barrier are reported for one of the branches of the HDN reaction network that leads to the formation of propylbenzene by hydrogenolysis of the C-N bond.