Stable isotopes for heavy element production

The synthesis of heavy elements and the search for new superheavy elements is one of the exciting fields in modern nuclear physics and chemistry. Heavy elements are produced by heavy-ion fusion reactions. Necessary prerequisites are intense heavy-ion beams from pure isotopic material and thin isotopically enriched targets. At GSI the elements from 107 to 112 were produced using targets of Pb and Bi and beams of the most neutron rich isotopes of Cr, Fe, Ni, and Zn.¹ We present the experimental set-up consisting of target wheel, velocity filter SHIP (Separator for Heavy Ion Reaction Products), and detector system. We shortly describe the status of the ion source techniques for delivering intense and stable beams for this kind of experiment.² The manufacturing and properties of various source - target combinations used for the synthesis of the elements by now are discussed in detail as well as the possibilities for extending the experiments into the region of superheavy elements.³     

Chemistry of thienopyridines. XXV. Comparative mass spectra of some amino and acylamino derivatives

Electron-impact mass spectral fragmentation patterns are reported for various aminothieno-pyridines (TPNH₂) and aeylaminothtenopyridines. The molecular ion TPNH₂⁺ shows loss of atomic hydrogen, hydrogen cyanide and both thioformyl radical and cation. TPNH₂⁺ is the most abundant ion in the spectrum of each acylamino compound investigated. A semiquanti-tative mass spectrum of the amine TPNH₂ can be obtained by deletion of selected peaks (for the acetylium and molecular ions) from the observed mass spectrum of the A-acetyl derivative.     

Kinetics of reduction of cinnamaldehyde by means of hydrido- and deuteridocobalt tetracarbonyl

The reaction of HCo(CO)₄ ( HT ) or DCo(CO)₄ ( DT ) with excess cinnamaldehyde ( CA ) in methylcyclohexane ( RH ) at 22.2° and under 1 atm of CO follows pseudo-first-order kinetics in HT or DT with an inverse isotopic effect of 0.54. Identified products of the reaction are hydrocinnamaldehyde ( HCA ) and styrene ( STY ). The STY is believed to be an artifact of the thermal decomposition of the true product PhCH₂CH₂C( (DOUBLE BOND) O)Co(CO)₄ ( X ) or its isomer. Reduction of the carbon-carbon double bond in CA is effected by hydrogen from both the cobalt compound and RH. It is proposed that the reaction involves a free-radical chain mechanism in which the rate of the slow step is proportional to [ CA ], the initial molar concentration of CA raised to a power of 1.5− 1.8. Additionally the rate of conversion of CA to HCA and X meets the criteria of a homocompetitive reaction with [ CA ], [ HCA ], and [ STY ] simple functions of t^0.5 (where t is reaction time) for use of DT or (in a single case) a function of (t^0.5 + t) for use of HT. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 473–481, 1997.     

Determination of Fluorescence Cross‐Sections of Biological Aerosols

Biological aerosols like pollen or bacteria can be differentiated from non‐biological aerosols as dust by fluorescence. Several organic substances contained in biological particles emit fluorescence light if they are illuminated with ultraviolet light. An instrument has been developed which generates aerosols of individual bacteria, illuminates them with light in the range of wavelengths from 220 to 570 nm and detects the spectra of fluorescence. The instrument has been tested on different species of bacteria showing that their fluorescence spectra are different.     

The neutralinos of theSU(N,1) minimal supergravity model and standard cosmology

We discuss the effect of the lightest supersymmetric particle (LSP), a Higgsino, and of the gravitino of theSU(N,1) minimal SUGRA model in the standard big bang theory. The freeze out of the LSP depends on the gravitino mass and on the top mass and leads to restrictive lower bounds for these parameters in the model. The decay of a gravitino with mass in the few TeV range leads to a delay in the cooling of the universe before nucleosynthesis. This constitutes the main bound on the gravitino mass of the model. The results are compared with the more standard “simultaneous decay approximation”.     

Free radical 4‐nitrophenylation of thieno[2,3‐b]pyridine. Part 2: Isolation and structural studies of three samples of mono (4‐nitrophenyl) products; relative yields of the five possible isomers

From the crude mixtures of isomeric 4‐nitrophenylthieno[2,3‐b]pyridines ( 3 ) previously reported [1] were isolated three analytically pure samples, viz. the 2‐isomer (yellow needles, mp 258°, 3a ), the 6‐isomer (red prisms, mp 182°, 3e ), and a ternary mixture of the 2‐, 3‐, and 4‐isomers (orange needles, mp 213°, 3a:3b:3c = 1.3:1.0:0.5). The 258° compound was identified as either 3a or 3b by its ¹H nmr spectrum and definitively as the former by its x‐ray crystallographic analysis. The isomeric identities of the 182° and 213° samples were established from their ¹H nmr spectra only. No 5‐isomer ( 3d ) was identified. Semi‐quantitatively, relative isomeric yields fit the pattern 2‐ (64%)>>6‐ (14%)≥3‐ (12%)>4‐ (6%)≥5‐(≤4%). Crystallographic data for 3a are presented.     

New Building Blocks for the Design of Oligonuclear Copper Complexes Based on Amino Carbohydrates

Remarkably high magnetic coupling and O(2)-activation ability analogous to that of catechol oxidase are characteristics of the first structurally defined, low-symmetry oligonuclear copper complexes of tridentate beta-oxoenamine ligands based on amino carbohydrates (the structure of a bis(acetylbutenonylaminoglucosidato)bis(μ-acetato)tricopper(II) complex is shown).     

Notiz über den Chloraufschluß niobhaltiger Substanzen

In an investigation on the decomposition of oxide minerals containing Ti, Nb, Fe, U and Y mixtures of TiO₂, Nb₂O₅, Fe₂O₃, U₃O₈ and Y₂O₃ have been heated in streaming Cl₂ containing SOCl₂. In order to avoid the formation of NbOCl₃, which is highly disturbing the distribution pattern of the chlorides, the reaction boat was covered with carbon powder. TiCl₄ was absorbed in sulphuric acid; NbCl₅, FeCl₃ and UCl₄ were condensed in the reaction tube and were separated by usual methods; YCl₃ remained in the reaction boat.