Rate constants for reactions of hydroxyl radicals with nitromethane and methyl nitrite vapours at 292 K

The variations of yields of CO₂ from the gas phase H₂O₂ + NO₂ + CO chain reaction system with added nitromethane or methyl nitrite have given rate constants for reactions of OH radicals with these substrates. At 292 K these are (5.5 ± 0.6) × 10⁸ and (8.0 ± 1.1) × 10⁸ dm³ mol^?1 s^?1 respectively.     

Microanalysis of unusual compounds. I Weighing hygroscopic samples

Summary A method is described for the construction of aluminium foil capsules in which hygroscopic samples may be dried to constant weight for combustion analysis.

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Zusammenfassung Die Herstellung von Kapseln aus Aluminiumfolie wird beschrieben. Hygroskopische Substanzen lassen sich darin bis zur Gewichtskonstanz trocknen, ehe sie analysiert werden.

     

Spectrophotometric determination of selenium with dithizone

Microgram amounts of selenium(IV) are determined by measuring the decrease in absorbance of dithizone in carbon tetrachloride solution at 620 nm. Relative standard deviations for samples containing 0.20 and 1.00 μg of selenium(IV) are 0.6% and 0.4%, respectively. Of several metals tested only copper (at the 1.0-μg level) and iron (at the 100-μg level) interfere but high concentrations of nitric or perchloric acid cause low results. A reinvestigation of the reaction of selenium(IV) with dithizone suggests a formula Se(HDz)₄ for the dithizonate.     

Alignment and orientation effects in resonant charge exchange from laser excited Na*(3p)

A collisional alignment and orientation study with planar symmetry is described, determining the complete density matrix for resonant charge transfer from laser excited atoms. Results are reported for the Na⁺+Na*(3p) system over the collision energy rangeE _c.m.=50?100 eV. We communicate the optimal alignment angle γ and linear polarisationP _l ⁺ of the charge cloud as well as its relative height ρ₀₀ and the angular momentumL _⊥ ⁺ transferred in the collision as a function of the scattering angle. For preparation of the sodium 3p orbital in the scattering plane (positive reflection symmetry) we observe that at small reduced scattering angles (<20 eV°) the preparation of apσ at large internuclear distances contributes most to the scattering intensity whereas at larger reduced scattering angles (>60 eV°) apπ⁺ preparation is more important. In contrast, preparation of thepπ^? orbital (perpendicular to the scattering plane) is large at small and vanishes at larger scattering angles. We conclude that orbital following cannot be assumed in this resonant charge transfer process. The angular momentum transfer is observed to be small, indicating only little coherence in the process, but shows nevertheless an interesting behaviour as a function of scattering angle.