The Rate Constant for Dissociative Electron Attachment to Ozone Revisited

The rate constant for dissociative electron attachment to ozone has been derived over the energy range from about 0 to 10 eV using recently measured and also corrected cross section data. The new rate constant data sets for two partial dissociative channels, as well as for the total dissociative electron attachment, are compared with previously reported values, and existing discrepancies are discussed.     

Electron attachment to oxygen and oxygen/ozone clusters studied in a high-resolution crossed beams experiment

Highly monochromatized electrons (with 30 meV FWHM) are used in a crossed beams experiment to investigate electron attachment to oxygen clusters (O₂)_n at electron energies from approximately zero eV up to 2 eV. At energies close to zero the attachment cross section for the reaction (O₂)_n +e → O ₂ ^? varies inversely with the electron energy, indicative of s-wave electron capture to (O₂)_n. Peaks in the attachment cross section present at higher energies can be ascribed to vibrational levels of the oxygen anion. The vibrational spacings observed can be quantitatively accounted for. In addition electron attachment to mixed oxygen/ozone clusters has been studied in the energy range up to 4 eV. Despite the initially large excess of oxygen molecules in the neutral clusters the dominant attachment products are undissociated cluster ions (O₃) _m ^? including the O ₃ ^? monomer while oxygen cluster ions (O₂) _n ^? appear with comparatively low intensity.     

Kinetik des Wachstums von Calciumhydroxid-Kristallen aus L?sung

Ohne Zusammenfassung     

Relaxing Phenomena in Negative Corona Discharge: New Aspects

Two theories, explaining the time dependence of the negative corona discharge current in air, are confronted with new experimental results. The influence of the ozone concentration on the discharge current was experimentally confirmed in dry air and in mixtures of nitrogen with oxygen. Assuming that only the dissociative electron attachment to ozone molecule is a process being responsible for a reduction of the electron component in the total mean discharge current, the mean value of the electron attachment rate constant k = (3 - 5.5) × 10^?9 cm^?3 s^?1 was derived from the measured dependence of the discharge current on the ozone concentration. The calculated value of the rate constant k corresponds to the dissociative attachment of electron to ozone molecule via process e + O₃ → products (O^? or O^?₂ negative ions).     

Operator algebras and a theorem of Dieudonne

LetA be aC*-algebra with second dualA″. Let (φ _n)(n=1,...) be a sequence in the dual ofA such that limφ _n(a) exists for eacha εA. In general, this does not imply that limφ _n(x) exists for eachx εA″. But if limφ _n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ _n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem.     

Influence of the Outer Electrode Material on Ozone Generation in Corona Discharges

The effect of the outer electrode material on negative corona discharge current and the process of ozone formation have been studied in coaxial cylindrical system of electrodes fed by dry oxygen. Three materials (brass, duralumin, stainless steel) were tested in experiments. The probability coefficient of ozone decomposition was found be slightly higher compared with known data. The coefficient of probability of ozone decomposition is decreasing with the time of exposition of the metal surface to mixture of oxygen and ozone. The effect of the electrode material on the current voltage characteristic of the discharge was marginal. In contrast to this at average energy density η higher than 10 J/cm³ the ozone concentration is affected by material of the outer electrode. A strong influence of the temperature of metal electrode on the probability coefficient of ozone decomposition was illustrated from the decrease of the ozone production.     

Comparative analysis and the coverage intervals of hair rare metal content in two Russian industrial centres

The existing data provide information on hair essential and toxic trace element content, whereas data on ultra-trace and rare elements are scarce. Therefore, the primary aim of the current study was to estimate hair levels and reference values of hair rare metal content using IUPAC recommendations in 2593 occupationally non-exposed adults living in Moscow and Novosibirsk (1900 women and 693 men). Hair Ag, Au, Ga, Ge, La, Rb, Tl, W and Zr content was assessed by inductively coupled plasma mass spectrometry with NexION 300D. Women were characterised by significantly higher hair Ag and Au levels than men, whereas men had increased La, Rb, Tl, W and Zr content as compared to women. Moscow inhabitants were characterised by significantly higher hair Au and Ge, and lower hair Ga, La, Rb, Tl, W and Zr content as compared to the ones from Novosibirsk. The coverage intervals of Ag, Au, Ga, Ge, La, Rb, Tl, W and Zr content in hair of the general sample of examinees calculated in accordance with IUPAC recommendations were 0.0278–0.2994, 0.0159–0.1812, 0.0062–0.0348, 0.0022–0.0066, 0.0023–0.0205, 0.0226–0.2083, 0.0002–0.0008, 0.0022–0.0120 and 0.0389–0.3521 μg/g, respectively. The obtained data indicate that both gender and geographical location affect hair rare metal content in adults.