Solvothermale Synthese und Bestimmung der Kristallstrukturen von AgBiI4 und Ag3BiI6

Solvothermal Synthesis and Crystal Structure Determination of AgBiI₄ and Ag₃BiI₆ AgBiI₄ and Ag₃BiI₆ were synthesized by solvothermal reaction from AgI and BiI₃ in diluted HI‐solution (20 %) at a temperature of 160 °C. The greyish‐black crystals grow as octahedra (AgBiI₄) or hexagonal/trigonal platelets (Ag₃BiI₆). AgBiI₄ crystallizes in space group Fd3¯m with a = 1222.3(1) pm (300 K) and Z = 8 whereas Ag₃BiI₆ shows the space group R3¯m with a = 435.37(6) pm, c = 2081.0(4) pm (300 K) and Z = 1. Both crystal structures show stacking sequence abcabc… of hexagonal layers containing Iodine. Bismuth and silver are sharing octahedral sites with different mass ratio in both structures. The part of silver which could be localized varies with temperature. This behaviour indicates mobility of silver within the crystal structure. The ionic conductivity of AgBiI₄ is explored. AgBiI₄ and Ag₃BiI₆ show close structural relationship, with AgBiI₄ as a variant with a higher degree of order.     

Synthesis of CoFe2O4 nanowire in carbon nanotubes. A new use of the confinement effect

Cobalt ferrite nanowires with an average diameter of 50 nm and lengths up to several micrometers were synthesized inside carbon nanotubes under mild reaction conditions using the confinement effect provided by the carbon tubular template.     

Theory of measurement of gas-adsorption equilibria by rotational oscillations

The gas adsorbed on the inner surface of a highly porous material like activated carbon or zeolite can be measured by slow damped oscillations of a torsional pendulum. The physical principles and the theory of this method are outlined. Formulas are given relating the increase in mass due to adsorption to changes of the frequency and the logarithmic decrement of slow, damped rotational oscillations of the pendulum. Preliminary measurements of gas adsorption equilibria of nitrogen on activated carbon show that the ratio of the mass adsorbedm, to the mass of the adsorbentm ^s , can be determined by this method with mean absolute error |m/m ^s |0.04%.Dedicated to the memory of Joseph Kestin (1913–1993).     

Application of ICP-MS radionuclide analysis to “Real World” samples of department of Energy radioactive waste

Germanium spectrometers must be operated at liquid nitrogen temperatures. Other detectors operate better when cooled. Many applications, because of hostile environments, inaccessibility, remote location, long duration, etc., are compromised, or totally precluded, by the requirement for liquid nitrogen. A Stirling cycle refrigerator based on a linear motor design, which is acoustically and vibrationally quiet, does not require secondary cooling, and operates unattended for years, is under development. System design and specifications are presented. Applications to cooled laser monitoring equipment. SQUID-based detection systems, environmental cleanup and monitoring, medical diagnostics, non-destructive testing systems, communication equipment, computer electronics, and imaging systems are discussed.     

Doppler-free laserspectroscopic investigations of hyperfine structure in the atomic cobalt spectrum

Performing Doppler-free laserspectroscopic investigations in the red wavelength region (640–670 nm) we were able to determine 10A-factors and 9B-factors of atomic cobalt levels. Now precise values of 18A-factors and 16B-factors of levels belonging to the configurations (3d+4s)⁹ are known. Fitting of the one-electron radial parameters to introduce agreement between experimental and theoretical hfs constants allows the prediction of hfs constants of not yet investigated fine structure levels. Values of the electric quadrupole moment of the Co⁵⁹ nucleus are determined in two electron configurations. The resulting mean value of the spectroscopic quadrupole moment isQ=0.35(3) barn.     

Mammalian cell growth studiedin situ by fourier transform infrared spectroscopy

Fourier transform infrared techniques were used to monitor mammalian cell growth plated on attenuated total reflection (ATR) crystals. Consistently, the growth kinetics plots generated from the obtained spectra demonstrated a sigmoidal curve representing a sequence of slow, rapid, then tapering cell growth which correlated well with non-spectral cell growth determinations. Significant advantages over traditional methods of measuring cell growth kinetics are demonstrated. The technique has promising potential to be used to study events in areas such as toxicology and cell biology.     

Trigonal-planare CuX3-Gruppen in Cu2Mo6X14, X = Cl,Br, I

Trigonal Planar CuX₃-Groups in Cu₂Mo₆X₁₄, X = Cl, Br, I Cu₂Mo₆Cl₁₄ (I), Cu₂Mo₆Br₁₄ (II) and Cu₂Mo₆I₁₄ (III) were synthesized by thermal treatment of corresponding mixtures of copper(I) and molybdenum(II) halides. The crystal structures were determined by single crystal X-ray analyses. I and II show isotypism, cubic, Pn3 (no. 201, sec. setting), Z = 4, I: a = 12.772(3) Å, II: a = 13.350(2) Å. III shows a new structural type, orthorhombic, Pbca (No. 61), Z = 4, a = 16.058(3) Å, b = 10.643(2) Å, c = 16.963(3) Å. Trigonal planar CuX₃ units were found in I? III. Structural behaviour relations are discussed, especially with regard to ionic conductivity.     

Excited-state electron-transfer quenching by a series of water photoreduction mediators

Rate constants k_q for the quenching of the excited state of Ru(bipy)₃²⁺ by a series of viologen salts having different redox potential E_{$\text{1}\text{2}$} have been determined in deaerated aqueous solutions at pH = 5 by laser flash photolysis. The k_q values are found to decrease with increasing —E_{$\text{1}\text{2}$} and to correlate with the reaction free-energy change ΔG. Such a correlation is shown to be consistent with the Rehm—Weller model for electron-transfer reactions.     

Time spectroscopy in theA 1∑ u + state of Li2

We have determined effective cross-sections for resonant transfer of excitation energy from state-selected Li₂ molecules to ground state Li atoms $$Li_2 A\left( {\upsilon ',J'} \right) + Li2S \to Li_2 X\left( {\upsilon '',J''} \right) + Li2P$$ with two different experimental techniques. Absolute cross-sections were derived from lifetime measurements of 114 rotational levels of theA-state subject to resonant collisions which belong to vibrational statesv′=4, 5, 6, 7 and 11 of⁶Li₂ and⁷Li₂. Cross-sections amount to several thousand Ų dropping off sharply with a resonance half-width of about 16 cm^?1. The resonance behaviour of the collision cross-section inferred from lifetime data could be confirmed by a double resonance technique probing the number of excited atoms with a second laser while the first laser was scanned over the Li₂ X?A absorption band. Due to their high reliability our data prove a good basis for the test of theoretical models. In contrast to earlier investigations significant deviations were found to exist between the measured cross-sections and those predicted by the first-order dipole-dipole scattering theory.     

Study of the direct detection of crosslinks in hydrocarbons by 13C-NMR. I. Preparation and characterization of model compound 1,1,2,2-tetra(tridecyl) ethane

The present series of papers is the commencement of a study aimed at the direct detection and quantification of crosslinking in hydrocarbons with the ultimate objective of a precise study of radiation-induced crosslinking in polyethylene. The subject of the present paper is the synthesis of a model compound containing a crosslink in a well-defined position sufficiently remote from the chain ends to be representative of an average crosslink in polyethylene. Such a compound in the form of 1,1,2,2-tetra(tridecyl) ethane has been synthetized and isolated in pure form in the course of the present work. Melting points and x-ray spacings of the new compound have been determined, and a comparison with the corresponding linear paraffins has been made. Effects are noted relating to the influence of molecular shape on the GPC elution volume, in which context an observation on a cyclic paraffin is also quoted.