Laboratoriumsapparate und Operationen

Ohne Zusammenfassung     

Lewis Base Sequestered Chalcogen Dihalides: Synthetic Sources of ChX2 (Ch=Se,Te; X=Cl,Br)

The synthesis and comprehensive characterization of a series of base‐stabilized ChX₂ (Ch=Se, Te; X=Cl, Br) is reported using aryl‐substituted diazabutadiene and 2,2′‐bipyridine (bipy) as the ligands. In stark contrast to free ChX₂ the complexes display excellent thermal stability. Their use as viable ChX₂ reagents that may be stored for later use is demonstrated in principle. The syntheses are simple and high‐yielding from commercially available or easily synthesized reagents. The bipy complexes are exceedingly rare examples of this ubiquitous ligand being utilized within Group 16 chemistry; the Se examples are the first to be characterized by X‐ray crystallography, and the Te species are only the second.     

Measurement of the third‐order nonlinear optical susceptibility χ(3) for the 1002‐cm–1 mode of benzenethiol using coherent anti‐Stokes Raman scattering with continuous‐wave diode lasers

The components of the third‐order nonlinear optical susceptibility χ⁽³⁾ for the 1002‐cm^–1 mode of neat benzenethiol have been measured using coherent anti‐Stokes Raman scattering with continuous‐wave diode pump and Stokes lasers at 785.0 and 852.0 nm, respectively. Values of 2.8 ± 0.3 × 10^–12, 2.0 ± 0.2 × 10^–12, and 0.8 ± 0.1 × 10^–12 cm·g^–1·s² were measured for the xxxx, xxyy, and xyyx components of |3χ⁽³⁾|, respectively. We have calculated these quantities using a microscopic model, reproducing the same qualitative trend. The Raman cross‐section σ_RS for the 1002‐cm^–1 mode of neat benzenethiol has been determined to be 3.1 ± 0.6 × 10^–29 cm² per molecule. The polarization of the anti‐Stokes Raman scattering was found to be parallel to that of the pump laser, which implies negligible depolarization. The Raman linewidth (full‐width at half‐maximum) Γ was determined to be 2.4 ± 0.3 cm^–1 using normal Stokes Raman scattering. The measured values of σ_RS and Γ yield a value of 2.1 ± 0.4 × 10^–12 cm·g^–1·s² for the resonant component of 3χ⁽³⁾. A value of 1.9 ± 0.9 × 10^–12 cm·g^–1·s² has been deduced for the nonresonant component of 3χ⁽³⁾. Copyright © 2011 John Wiley & Sons, Ltd.     

The nuclear size dependence of large momentum transfer scattering and quark interaction dynamics

A simple dynamical picture for hadron interactions is used to discuss the A dependence of large p_⊥ scattering and dilepton production. Observations in large p_⊥ experiments are explained. Important corrections to dilepton production cross sections are found, leading to acceptable agreement between colored-quark theory and experiment.     

A swinging arm calibration method for low velocity hot-wire probe calibration

This paper describes a swinging arm calibration facility for the calibration of hot-wire probes at low velocities. During the motion of the probe the anemometer signal is recorded digitally using pre-set angle positions for the start and stop of the data acquisition. The evaluation method described in this paper is based on an integral procedure over a fixed, known probe path length. Tests in the velocity range 1 to 6 m/s demonstrated a high degree of repeatability of the calibration results. Furthermore, the test facilities can easily be adjusted for other low velocity ranges.     

Low energy crossed beam study of the endothermic charge transfer reaction H+2(Ar,H2)Ar+

A crossed beam study of the title reaction if reported, from 0.45 to 7.8 eV. The reaction is predominantly translationally endothermic. At the lowest energy, there is evidence for two reaction paths: a long-range electron transfer and an intimate collision with electron transfer. Branching ratios for the competitive proton transfer reaction are presented.     

The determination of selenium status in the Australian diet using neutron activation analysis

Australia-wide samples of 50 representative foods from each of the State capitals were analysed for selenium by instrumental and radiochemical neutron activation analysis. Results were compared with State and Federal Regulations for toxic elements in foods as well as with recommendations by Australian and US authorities for safe and adequate dietary intake of this essential trace element.