Chelatbildung mit N-unsubstituierten 1.2-Diiminliganden

Fe^II, Co^III, Ni^II, Pd^II, and Rh^III chelates with the N-unsubstituted 1-2-diimine ligands benzildiimine and 9.10-phenanthrenequinonediimine have been prepared. The compounds are characterised chemically, spectroscopically (uv, vis, ir) and polarographically. The results indicate remarkable π-back bonding in the chelates. The unusual magnetic moments of the Fe^II, Co^III and Rh^III chelates are caused by temperature-independent paramagnetism. Fe^II, Co^III, Ni^II and Cu^II chelates of the partially deprotonated phenanthrenequinone diimine are obtained.     

CI study of rovibrational dependence of nuclear quadrupole coupling constants of all isotopic variants of OH+ in the X3Σ− state

The ¹⁷O and ²H quadrupole coupling constants of rovibrational levels of ¹⁷O¹H⁺, ¹⁷O²H⁺, and ¹⁶O²H⁺ in their X³Σ⁻ state have been calculated from molecular wave functions that explicitly describe nuclear motion. The ¹⁷O quadrupole coupling is predicted to be strong and its vibrational dependence differs from that known for other nuclei A in the first-row hydrides AH or AH⁺. The deuterium coupling in ¹⁷O²H⁺ and ¹⁶O²H⁺ is found to be weak and its behavior is similar to that of other first-row hydrides. The change with rotational excitation is unimportant. The quadrupole hyperfine patterns of ¹⁷O²H⁺ in its ground state are dominated by the strong oxygen coupling. © 1996 John Wiley & Sons, Inc.     

Electrochemical activity of rhodium complexes supported on fibrous-carbon material

The redox properties of heterogenized Rh^I, Rh^II, and Rh^III complexes with different, particularly organophosphorus, ligands were studied by cyclic voltammetry (CVA). The support is a carbon-paste electrode based on a fibrous-carbon material and activated carbon. The electrochemical reduction of Rh^III produces Rh metal, which further catalyzes hydrogen evolution. After the reduction of water-soluble binuclear Rh^II complexes, the CVA curves exhibit peaks of electrocatalytic hydrogen evolution and irreversible Rh^I→Rh^II oxidation. The Rh^II complexes with organophosphorus ligands are characterized only by the peak of Rh^I→Rh^II oxidation. After reduction, the Rh^I complexes behave as a pseudo-reverse Rh⁰/Rh^I pair. The electron-donating properties of the ligand determine the reversibility of the system. The degree of structurization of the carbon matrix and the presence of phosphorus(v) atoms in it affect the electrochemical activity of the Rh^II and Rh^I complexes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 908–914, May, 1999.     

Production of charge-induced X-rays during PIXE studies using light and heavy ion-beams

A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of¹H⁺,¹H₂ ⁺,²H⁺,²H₂ ⁺,³He⁺,³He²⁺,⁴He⁺,¹⁴N⁺,¹⁴N²⁺,¹⁶O⁺ and²⁰Ne⁺ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.     

Purification of waste waters containing 60Co2+, 115mCd2+ and 203Hg2+ radioactive ions by ETS-4 titanosilicate

Summary The sorption of ⁶⁰Co²⁺, ^115mCd²⁺ and ²⁰³Hg²⁺ from diluted solutions (as analogues for radioactive waste waters) on ETS-4 microporous titanosilicate was studied at 277, 293, 313 and 333 K by measuring the sorption kinetics using a batch-method. The sorption of these radiocations was compared by means of the distribution coefficient and of the sorption capacity. The maximum sorption capacities follow the order: ²⁰³Hg²⁺>^115mCd²⁺3⁶⁰Co²⁺. The thermodynamic functions of the sorption processes have been estimated. The increase of the absolute value of DG° with increasing temperatures shows that higher temperatures favor ionic exchange.     

Synthesis of a Dithiocarbamate Chelate Resin and Its Oxidized form and Their Adsorption Properties for Heavy Metal Ions

A series of macroporous dithiocarbamate chelate resins, III and V, and an oxidized resin, VI, with high adsorption capacity were prepared. The influence of various reaction conditions of amination, dithiocarboxylation, and oxidation were examined. The structure and the conversion of functional groups of resins were confirmed by IR spectra and elemental analysis. The adsorption capacities of Resin II for Hg²⁺, Cu²⁺, Zn²⁺, and Cd²⁺ are 4.40, 2.44, 1.77, and 1.36 mmol/g, respectively. The adsorption capacities of Resins V and VI for Cu²⁺. Zn²⁺, Ni²⁺, Co³⁺, Ag⁺, Hg²⁺, Cd²⁺, Pb²⁺, and Au³⁺ are 4.07–0.51 and 3.81–0.59 meq ion/g, respectively. The adsorption rate and the influence of pH on the adsorption percentage of the resins for metal ions were examined. Noble metal, transitional metal, and heavy metal ions can be quantitatively adsorbed by the resins. The adsorbed Cu²⁺, Pb²⁺, Cd²⁺, Co³⁺, and Ni²⁺ can be quantitatively eluted with 5N HNO₃, and the presence of large amounts of Ca²⁺, Mg²⁺, Fe³⁺, and Al³⁺ did not interfere.     

A Highly Selective Colorimetric Sensor for Cu2+ Based on Phenolic Group Biscarbonyl Hydrazone

A novel copper selective sensor 2 based on hydrazide and salicylaldehyde has been designed and prepared. Sensor 2 behaves a single selectivity and sensitivity in the recognition for Cu²⁺ over other metal ions such as Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Zn²⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, Cr³⁺ and Mg²⁺ in DMSO. The distinct color change and the rapid changement of fluorescence emission provide naked‐eyes detection for Cu²⁺. The UV‐vis data indicate that 1:2 stoichiometry complex is formed by sensor 2 and Cu²⁺. The association constant K_s was 3.51×10⁴ mol^?1·L. The detection limitation of Cu²⁺ with the sensor 2 was 2.2×10^?7 mol·L^?1. The sensing of Cu²⁺ by this sensor was found to be reversible, with the Cu²⁺‐induced color being lost upon addition of EDTA.     

Natural radioactivity distribution in geological matrices around Kaiga environment

Summary The activity and absorbed dose rate of the naturally occurring radionuclides, viz. ²³⁸U, ²³² Th and ⁴⁰K were determined in soil and rock samples collected around Kaiga site. The mean activity levels (Kaiga soil) of naturally occurring ²³² Th are comparable with that in worldwide soil, while concentrations of ²³⁸U and ⁴⁰K are lower than those in worldwide soil. The absorbed dose rate in outdoor air ranged 20-58 nGy ^. h^-1 with a mean of 33.3 nGy ^. h^-1, which is below the world average of 60 nGy ^. h^-1. The total effective dose rate in outdoor air for soils ranged 25.6-74.4 mSv ^. y^-1 with a mean of 43.0 mSv ^. y^-1. The estimated dose rate at Kaiga is comparable with that estimated at Kakrapar and Rawatbhata and much less than that estimated at coastal sites of India.     

Studies on some radical transfer reactions by entrapping the radicals as polymer endgroups. III. Reaction of ȮH radical with halide ions

The reactions of OH radical with Cl^?, Br^?, I^?, and F^? ions have been studied by entrapping the product radicals as polymer endgroup which have been detected and estimated by the sensitive dye partition technique. The rate constants of the reactions with Br^?, Cl^?, and F^? ions have been determined to be 1.51 × 10⁹, 1.32 × 10⁹, and 0.92 × 10⁹ L mol^?1 s^?1, respectively at 25°C and pH 1.00. Oxidation of I^? ions liberates I, which inhibits the polymerization and the reaction could not be followed by polymer endgroup analysis. The observed order of reactivity Br^? > Cl^? > F^? is in accordance with the electron affinities of the halide ions. The acidity of the reaction medium has a strong influence on the rate of reaction. With Br^? ions, the rate constant of the reaction falls from 1.51 × 10⁹ to 0.75 × 10⁹ L mol^?1 s^?1 at 25°C as the pH is raised from 1.0 to 2.8. The method is simple and accurate and can be applied to study very reactive radicals.     

Chemiluminescent ion-molecule reactions in the system C+ + H2

The optical emission resulting from collisions between C⁺ ions and H₂ gas was measured in the energy range 2 to 20 eV_c.m.. The observed spectrum consists mainly of the CH⁺ A ¹Π → X ¹Σ⁺ band system; CH⁺ (A ^fΠ) is shown to be formed in the chemiluminescent reactio: C⁺(²P⁰) + H₂ → CH⁺(A ¹Π) + H(²S). The energy dependence of the emission cross section was measured. The occurrence of this reaction is discussed in terms of a electronic state correlation diagram for the system.     

Study of ion transport processes in soils by radioabsorption method

The transport processes of Na⁺, K⁺, Cs⁺, Ca²⁺, Zn²⁺, Mn²⁺, Fe³⁺ and HPO ₄ ²⁻ ions were studied in soils by radioabsorption method. The effective diffusion coefficients varied in the interval of 10⁻¹⁶–10⁻¹⁰ m²s⁻¹. The effective diffusion coefficient of Ca²⁺, Co²⁺, Zn²⁺ and Fe³⁺ ions increased by several orders of magnitude as a result of the addition of a complex forming agent.     

Depth distribution of239,240Pu and137Cs in soils of South Korea

Depth distribution of^239,240Pu and¹³⁷Cs in the soils of South Korea have been studied. The average accumulated depositions were estimated roughly to be 54.8±32.1 Bq·m^–2 for^239,240Pu, 1.6±1.0 Bq· ·m^–2 for²³⁸Pu and 1982.8±929.1 Bq·m^–2 for¹³⁷Cs. The activity ratios of^239,240Pu/¹³⁷Cs in soils were found to be in the narrow range of 0.0153 to 0.0364 with a mean value of 0.0230±0.006. The concentrations of^239,240Pu and¹³⁷Cs in soils decrease exponentially with increasing the soil depth. A significant correlation was found between the concentration of^239,240Pu and that of¹³⁷Cs. The activity ratios of^239,240Pu/¹³⁷Cs tend to increase slightly with increasing soil depth.     

Radioactivity of coal and ashes from Figueira coal power plant in Brazil

Summary The Figueira coal-fired power plant (CFPP) is among the Brazilian CFPP which presents higher uranium concentration. Gamma-ray spectrometry was used to determine ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³² Th and ⁴⁰K contents in pulverized coal, furnace bottom ash and fly ash samples. The natural radionuclide concentrations in pulverized coal ranged from 813 to 2609 Bq ^. kg^-1 for U series and from 22 to 40 Bq ^. kg^-1 for ²³² Th. The fly ash fraction gave concentrations ranging from 1442 to 14641 Bq ^. kg^-1, for uranium series. The same enrichment factor was observed for ²³⁸U, ²²⁶Ra and ²³² Th. Only ²¹⁰Pb and stable Pb presented a high enrichment factor for the last stage filter fly ash. The concentration of the uranium series found in the ashes is close to the limit adopted by the Brazilian guideline (CNEN-NN-4.01).²² Therefore, it is advisable to evaluate the environmental impact of the installation.     

Simultaneous determination of210Bi and210Po on pine needles by solvent extraction and liquid scintillation counting

A determination procedure has been developed for²¹⁰Bi and²¹⁰Po in environmental samples and was applied for pine needles. Bismuth-210 and²¹⁰Po separated from the parent nuclide²¹⁰Pb as BiOCl precipitate were extracted simultaneously by TOPO/toluene containing PPO and POPOP. The separation of²¹⁰Bi and²¹⁰Po from²¹⁰Pb was almost satisfactory. The activity of²¹⁰Bi+²¹⁰Po in the TOPO/toluene was measured periodically by liquid scintillation counting for about 20 days after separation. The time course of the decreasing pattern of the activity was determined by the initial activity ratio²¹⁰Po/²¹⁰Bi. The decreasing pattern of the activity was compared with theoretical patterns, and best estimates for²¹⁰Po and²¹⁰Bi were obtained by non-linear least-squares fitting. The activities of²¹⁰Bi and²¹⁰Po were determined for one-year and two-year old pine needles fro the same pine tree, and weathering half-time and deposition rate of these nuclides was discussed.     

Theoretical study of electronic structure of rhodium mononitride and interpretation of experimental spectra

Potential energy curves of 22 electronic states of RhN have been calculated by the complete active space second‐order perturbation theory method. The X¹Σ₀⁺ is assigned as the ground state, and the first excited state a³Π₀+ is 978 cm^?1 higher. The ¹Δ(I) and B¹Σ⁺ states are located at 9521 and 13,046 cm^?1 above the ground state, respectively. The B¹Σ⁺ state should be the excited state located 12,300 cm^?1 above the ground state in the experimental study. Moreover, two excited states, C¹Π and b³Σ⁺, are found 14,963 and 15,082 cm^?1 above the X¹Σ⁺ state, respectively. The transition C¹Π₁–X¹Σ₀⁺ may contribute to the experimentally observed bands headed at 15,071 cm^?1. There are two excited states, D¹Δ and E¹Σ⁺, situate at 20,715 and 23,145 cm^?1 above the X¹Σ⁺ state. The visible bands near 20,000 cm^?1 could be generated by the electronic transitions D¹Δ₂–a³Π₁ and E¹Σ⁺₀–X¹Σ⁺₀ because of the spin–orbit coupling effect. © 2013 Wiley Periodicals, Inc.     

Efficiency calibration of HPGe detector in far and close geometries

The absolute total and full-energy peak (FEP) efficiencies of a high purity germanium (HPGe) photon detector are measured in the energy range from 40 keV to 1500 keV. The functional parameters are fitted to the calibration points from 14 long-lived standard sources (¹²⁹I,²⁴¹Am,¹⁰⁹Cd,⁵⁷Co,¹³⁹Ce,¹³⁷Cs,⁵⁴Mn,⁶⁵Zn,⁶⁰Co,²²Na,¹³³Ba,¹⁵²Eu,¹⁵⁴Eu and^166mHo) within an accuracy better than the quoted uncertainty of the calibration sources. The efficiencies in far and close geometries are compared.     

A Lead‐Selective Membrane Electrode Based Upon a Phosphorylated Hexahomotrioxacalix[3]Arene

Solvent extraction of a mixture of Pb^II, Mn^II, Fe^III, Co^II, Ni^II and Cd^II in aqueous perchlorate medium by a phosphorylated hexahomotrioxacalix[3]arene (calix‐3) in dichloromethane shows a significant selectivity towards lead ions. The ligand can also be incorporated into a membrane to provide a new lead ion‐selective electrode (Pb^II‐ISE). A plasticized PVC membrane containing 30% PVC, 53.5% ortho‐nitrophenyloctylether (NPOE), 4.5% sodium tetraphenylborate (NaTPB) and 12% ionophore was directly coated on a graphite rod. This sensor gave a good Nernstian response of 29.7 ± 0.7 mV decade^?1 over a concentration range of 1 × 10^?8 – 1 × 10^?4 M of lead ions, independent of pH in the range 3‐7, with a detection limit of 0.4 × 10^?8 M. The dynamic response time of the electrode to achieve a steady potential was very fast and found to be less than 7 s. The selectivity relative to Ag⁺, NH₄⁺, Li⁺, Na⁺, K⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Fe³⁺, La³⁺, Sm³⁺, Dy³⁺, Er³⁺, Y³⁺ and Th⁴⁺ was examined. The electrode exhibits adequate stability with good reproducibility (with a slope of 29.6 ± 1.5 mV for 8 weeks). The characteristics of the sensor are compared with those of a tetraphosphorylated calix[4]arene (calix‐4) based Pb^II‐ISE, reported recently. The electrode was successfully used as an indicator electrode for a potentiometric titration of a lead solution using a standard solution of EDTA. The applicability of the sensor for lead ion measurements in various synthetic samples was also investigated.     

Adsorption of tracer cations,and the separation of carrier-free95Nb from95Zr,XU1 from U and45Ca from46Sc on titanium phosphate column

Titanium phosphate as ion exchanger for column operation has been prepared by mixing TiCl₄ and H₃PO₄ in suitable proportion. The ratio of titanium: phosphate was obtained to be 1:2.02. The uptake of Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺, Sc³⁺, Co³⁺, Y³⁺, Tb³⁺, Zr⁴⁺ and Th⁴⁺ cations at very small concentrations has been studied on this exchanger. The data indicated that the different cations are adsorbed in the exchanger by different mechanisms. Radiochemical separations of carrier free⁹⁵Nb from⁹⁵Zr, UX₁ from U and⁴⁵Ca from⁴⁶Sc have been achieved by adopting very simple chemical procedures through a column of titanium phosphate. The -spectrum of the separated⁹⁵Nb, UX₁ and⁴⁶Sc showed that the products are of high radionuclidic purity. The individual separation procedures took less than 20 min and the yields are quantitative.     

Radionuclides in a sediment trap and bottom sediment samples from the eastern Turkish coast of the Black Sea

Summary Radionuclide (¹³⁷Cs, ²³⁸U, ²³²Th and ⁴⁰K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish coast of the Black Sea. The specific activity of the ¹³⁷Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq^. g^-1dry weight. The calculated flux rate of the ¹³⁷Cs was between 0.37 and 2.59 Bq^. m^-2. d^-1in the sampling periods of 2002 and 2003. The ¹³⁷Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq^. g^-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the 17 years after the Chernobyl accident.     

Determination of radionuclides in the environment using gamma-spectrometry

Summary Seventy nine samples, including soil and rock, were collected from the agrestic region of the State of Pernambuco, Brazil. The activity concentrations of ²³⁸U and ²²⁶Ra in the samples were determined by gamma-spectrometry using an HPGe detector. The concentrations of ²³⁸U were 22 Bq ^. kg^-1 to 22 kBq ^. kg^-1. The concentrations of ²²⁶Ra were 14 Bq ^. kg^-1 to 17 kBq ^. kg^-1. The ²³⁸U/²²⁶Ra ratios in the soil were 0.7 to 3.4 (arithmetic mean 1.7). The radiometric data were evaluated to explain ²³⁸U and ²²⁶Ra migration in the soil and the possible consequences to the environment.