ENDOR investigations of Ge doped GaP

ENDOR measurements of germanium doped gallium phosphide show a SHF-interaction with one neighbour shell strong enough to resolve the splitting of lines caused by the mutual interaction of the different nuclei of the same shell. The symmetry and hyperfine parameters of four other neighbour shells have also been determined.     

Paramagnetische Wasserstoffzentren in Kaliumjodid

After irradiation with ultraviolet light at low temperature KJ crystals doped with SH^? or SeH^? ions show the ESR spectra of interstitial hydrogen atoms (U ₂ centers). The behavior of the spectra is studied at 9 and 35 GHz respectively, and the parameters of the spin Hamiltonian have been determined. Forbidden transitions with changes Δm=±1 of the nuclear quantum number are found to occur with appreciable intensity in KJ. Above 95 K the hydrogen atoms become unstable and react to new paramagnetic hydrogen centers.     

A paramagnetic defect in ZnO: Sn with (5s)1 configuration

A not photosensitive electron spin resonance signal due to Sn³⁺ in ZnO is observed. It is found that theg shift is negative and that the zero field splitting has the smallest value for all zinc compounds. The energy level diagram has been calculated by a computer program for an axial crystal field symmetry and a zero field splitting which is comparable to the microwave quantum.     

Eigenst?rstellen in elektronenbestrahltem Zinkoxid

The ESR of zinc oxide single crystals irradiated with 6 × 10¹⁸ electrons/cm² consists of five spectra resulting from interstitial oxygen ions and from holes trapped at zinc vacancies. Irradiation with visible light during the ESR measurements allows to determine the energy levels of the centres. Further the influence of the paramagnetic defects on the electric conductivity is discussed.     

Ein „F-Zentrum” als paramagnetischer Donator in Zinkoxid

The ESR line atg?1.96 in zinc oxide single crystals has been reinvestigated. It is found that the defect responsible for the resonance can be described as anF-center, i.e., an electron trapped in an oxygen vacancy. TheF-centers act as donors and due to overlapping of their wave functions give rise to donor band conduction. This model has been confirmed by studying various methods to produce the centers and by ESR and conductivity measurements down to liquid helium temperature.     

Vibrational spectra of chalkogen hydride molecules in alkali halides

A report is given on the u.v. and visible flourescence of cesium halides and RbBr doped with chalkogen hydrides, where a molecular vibrational structure of the spectra is resolved. Preliminary data for the parameters of an anharmonic oscillator model are given.     

Paraquat induces oxidative stress, neuronal loss in substantia nigra region and Parkinsonism in adult rats: Neuroprotection and amelioration of symptoms by water-soluble formulation of Coenzyme Q10

Background  

Parkinson's disease, for which currently there is no cure, develops as a result of progressive loss of dopamine neurons in the brain; thus, identification of any potential therapeutic intervention for disease management is of a great importance.     

Why should transition metal chalcogenides be investigated as water splitting precatalysts even though they transform into (oxyhydr)oxides?

The extensive investigation of 3d transition metal chalcogenide (sulphides, selenides, tellurides) precatalysts has shown that they transform into (oxyhydr)oxides during the oxygen evolution reaction (OER) and likely during industrial hydrogen evolution reaction (HER) conditions, as predicted by their Pourbaix diagrams. The phases formed from chalcogenide precatalysts are often more active, due to anion leaching induced effects. But are chalcogenides suitable to be used sacrificially, are they abundant, cheap, and non-toxic enough? Is their unique chemical nature really required? This review answers these questions by discussing the role of chalcogenides in the reconstruction/transformation process. Furthermore, it examines the role of remaining traces of chalcogenates (sulphate, selenate) that were recently shown to improve the OER activity and can break the 1OH/1OOH scaling relations.     

HYDRATED ELECTRON FORMATION IN NANOSECOND and PICOSECOND LASER FLASH PHOTOLYSIS OF HEMATOPORPHYRIN IN AQUEOUS SOLUTION

Nanosecond (lambda exc = 266, 355 and 532 nm) and picosecond (lambda exc = 355 nm) laser flash photolysis of hematoporphyrin (Hp) was performed in neutral (pH 7.4) and alkaline (pH 12) aqueous solution, as well as in the presence of 0.1% Triton X-100. The dependence of the yield of photoproduced hydrated electrons (e-aq) on laser pulse energy was studied over a wide range of energies (0.2 to greater than 1000 mJ cm-2). The results show that e-aq are predominantly formed in a two-photon process at lambda exc = 266 and 355 nm. One-photon quantum yields are higher at lambda exc = 266 nm than at lambda exc = 355 nm. Both one-photon and two-photon pathways are less efficient at higher Hp concentration, reflecting the influence of Hp self-aggregation. Two-photon e-aq formation is more efficient when 30 ps pulses are used for excitation, as compared to 10 ns pulses. No e-aq could be detected at lambda exc = 532 nm. Nanosecond pulse-induced transient spectra obtained at pH 7.4 are also discussed.