Die Bestimmung der Malons?ure durch Kaliumpermanganat

Ohne Zusammenfassung     

Synthesis and near-infrared luminescence of a deuterated conjugated porphyrin dimer for probing the mechanism of non-radiative deactivation

beta,meso,beta-Fused porphyrin oligomers have many attractive photophysical features such as strong absorption in the near-IR at wavelengths greater than 1000 nm, and high two-photon cross sections. However their ultrafast S(1)-S(0) deactivation (k(d) > 10(11) s(-1)) limits potential applications. We have synthesised a deuterated fused porphyrin dimer to test whether deuteration influences the rate of non-radiative deactivation. An efficient synthetic strategy was developed, starting with deuteration of dipyrromethane. Deuteration of the zinc porphyrin dimer does not affect its fluorescence quantum yield in CD(2)Cl(2)(Phi(fD)/Phi(fH)= 1.00 +/- 0.05). This implies that the ultrafast non-radiative deactivation is not simply a consequence of the small S(1)-S(0) energy gap. Comparison with other conjugated porphyrin oligomers confirms that the deactivation rate in the edge-fused oligomers is faster than would be expected from the energy gap law. This result indicates that it should be possible to create near-IR dyes with similar S(1)-S(0) energy gaps to the beta,meso,beta-fused porphyrin oligomers but with slower rates of S(1)-S(0) decay.     

The four states of the Massless neutrino with pauli coupling by Spin-Gauge invariance

The Pauli coupling is introduced for four-component neutrino states and related to local T ⁴SU(2,2) spin-gauge (not internal symmetry) transformations applied to the massless Dirac equation. The well-known left-right asymmetry for free neutrino helicity states is generalised and discussed for Pauli-coupled neutrinos. An explicit exact solution is obtained for Pauli-coupled neutrino equations in an external free radiation field by the use of the above local spin-gauge transformations. It is also suggested that local SL(2, C)SU(2,2) spin-gauge transformations can be used to obtain models of neutral currents for neutrinos.     

Reactions of CH3OCH2+ with hydrocarbons and O,N, and S compounds: applications for chemical ionization in selected ion flow tube studies

We report the results of a flowing afterglow ion source-selected ion flow tube study (FA-SIFT) of the reactions of the methoxymethyl cation, CH3OCH2+. Rate coefficients and product branching ratios are reported for twenty nine reagent molecules including those that constitute the major ingredients of air, the hydrocarbons CH4, C2H6, C3H8, n-C4H10, C2H2, C2H4, C3H4 (allene and propyne), C6H6, and the S-containing molecules H2S, CH3SH, C2H5SH, (CH3)2SH, and (C2H5)2SH. In addition, we examined the reactions with the N-containing molecules NH3, CH3NH2, (CH3)2NH, (CH3)3N, pyrrole, pyridine as well as CH3COCH3. The results can be summarized under three general reaction types: Reaction at the CH3 carbon, reaction at the CH2 carbon, and association. The results also indicate that the methoxymethyl cation can be used as a chemical ionization source for the detection of trace levels of S-containing compounds in saturated hydrocarbons.     

Ethical guidelines for publication in journals and reviews

EuCheMS—The European Association for Chemical and Molecular Sciences is a nonprofit association. Its objective is to promote cooperation in Europe between those nonprofit scientific and technical societies and professional institutions in the field of chemistry/chemical sciences whose membership consists largely of individual qualified chemists/chemical scientists and whose interests include the science and/or practice of chemistry/chemical sciences. It was founded in 1970 and currently has 50 member societies in 36 countries. Published in Russian Zhurnal in Analiticheskoi Khimii, 2007, Vol. 62, No. 4, pp. 441–444. The text was submitted by the authors in English.     

Monitoring chloramines and bromamines in a humid environment using selected ion flow tube mass spectrometry

The selectivity and sensitivity of selected ion flow tube mass spectrometry (SIFT‐MS) for individual breath analysis of haloamines has been improved by heating the flow tube in a commercial instrument to around 106°C. Data is presented showing the marked reduction in the number density of water clusters of product ions of common breath metabolites that are isobaric with the product ions from monochloramine and monobromamine that are used to monitor the haloamine concentrations. These results have direct relevance to the real‐time monitoring of chloramines in drinking water, swimming pools and food processing plants. However, once the isobaric overlaps from water cluster ions are reduced at the higher temperatures, there is no conclusive evidence showing the presence of haloamines on single breath exhalations in the mid parts per trillion range from examination of the breaths of volunteers. Copyright © 2010 John Wiley & Sons, Ltd.     

Thermal energy charge transfer reactions of acetone and biacetyl

Rate coefficients up to a factor of 2.5 times larger than the capture collision rate are reported for a series of thermal energy, positive ion-molecule reactions of acetone and biacetyl. These rapid rates are interpreted in tems of a dissociative charge transfer process in which an electron is transferred in a non-spiralling collision from outside the classical capture limit. The factor which lead to this type of mechanism are discussed briefly.     

Dissociation energy of the NH3 · Hg(P0) complex

A phase-shift method has been used to study the bimolecular and termolecular reactions of Hg(³P₀) with NH₃. The bimolecular and termolecular rate constants are 3.8 × 10⁻¹³ cm³ molecule⁻¹sec⁻¹ and 1.4 × 10⁻³⁰ cm⁶ molecule⁻²sec⁻¹, respectively. From the difference between the wavelengths of peak emission intensity for the stabilized and unstabilized Hg·NH₃ complexes the dissociation energy of the complex is estimated to be 5.0 kcal mole⁻¹.