Variational calculations of the lowest 2S and 2P states of the Li atom

The lowest variational upper bounds to the lowest ²S state of ?7.478044 au and to the lowest ²P state of ?7.410097 au of the lithium atom are obtained.     

Deactivation of He 23S by thermal electrons

The rate coefficient for deactivation of the metastable 2³S state of He by impact of thermal electrons is deduced from recent calculations of inelastic electron-He cross sections. The deactivation rate is found to be nearly constant with temperature. Computed values range between 2.82 and 3.03 (10^?9 cm³/sec) for T between 0 and 2000°K. De-excitation cross sections are given for low-energy incident electrons.     

Ein Verfahren zur simultanen Messung von 3H und 35S

Ohne Zusammenfassung     

Excitation of alkali atoms in collisions with molecules. Population of the states K(62S) and K(52-P)

Radiation at 4050 and 6930 A has been observed in collisions of fast potassium atoms with N₂, O₂, CO, NO, CO₂, C₂H₄ and C₆H₆. Emission at both wavelengths is weak compared to that at 7680 Å. The threshold energy for emission at 6930 Å has been found to be equal to the excitation energy (3.4 eV) of the state K(6²S) for N₂ and NO, but higher (5.5 eV) for CO.     

Velocity dependence of the penning ionization cross section of D atoms by He (2 1S) and He (2 3S) atoms

Measurements of the Penning ionization cross section, σ_PI of D atoms by metastable He atoms show that σ_PI for the reaction He (2 ¹S) + D is much larger than σ_PI for He (2 ³S) + D. In the relative velocity range ν_r = (2.3–4.8) × 10⁵ cm/s (0.037–0.163 eV), σ_PI for He (2 ¹S) + D collisions was found to vary as ν_r^?0.33.     

Reactions of metastable calcium 3P: quenching by Ca(1S), Mg1S) and inert gases

Rate constants have been measured (by laser induced fluorescence) for the quenching of metastable Ca(³P) by the ground states of Ca and Mg and by the inert gases. Rate constants for the metals were considerably larger than for the inert gases. The cross sections for the inert gases are well correlated by an orbiting model.     

Synthesis of 2,4-dichlorophenyl methanesulfonate labeled with 14C and 35S

Radioactive 2,4-dichlorophenyl methanesulfonate labeled with ¹⁴C and ³⁵S has been synthesized because it was needed to facilitate the study of the metabolic fate of this interesting nematicide. It was prepared from the reaction between methanesulfonyl chloride and 2,4-dichlorophenol in the presence of a base. Three hundred milligrams of each ¹⁴C- and ³⁵S-2,4-dichlorophenyl methanesulfonate was obtained in a yield of 87% based on ¹⁴C-2,4-dichlorophenol or ³⁵S-methanesulfonyl chloride, respectively. The specific activity was 3.8 mCi/mmol for the compound labeled with ³⁵S and 2.5 mCi/mmol for the ¹⁴C material. Both tracers assayed over 99% after purification.     

Total and ionization cross sections for He*(23S)-Ar and He*(21S)-Ar in the thermal energy range

Integral total and integral ionization cross sections of He^*(2³S)-Ar and He^*(2¹S)-Ar have been measured in the c.m. collision energy range 2–230 meV. The data are compared with optical potential calculations giving preliminary fits which are discussed.     

Instrumentelle Kompensation des Quencheffektes bei der Bestimmung von 14C und 35S

Zusammenfassung Ein Quencheffekt tritt auch nach Oxydation der organischen Probe auf. Dieser ist bedingt durch gewisse Verbrennungsprodukte, wie NO₂, Halogene, SO₂ und SO₃. Es wurde gefunden, da\ man den Quencheffekt der Verbrennungsprodukte bei der Bestimmung von ¹⁴C und ³⁵S ausschalten kann, wenn man die Spannung des Data-Photomultipliers bis zu einem gewissen Punkt (Kompensationspunkt) erhöht und die Messung in einem ZÄhlfenster durchführt. Der Kompensationspunkt wird graphisch ermittelt; hierzu mi\t man die ZÄhlrate des reinen Absorbens sowie die ZÄhlrate des Absorbens, das die maximal zu erwartende Menge Verbrennungsprodukt enthÄlt, bei verschiedenen Data-Spannungen. Der Zusammenhang zwischen der instrumenteilen Kompensation und dem Energiespektrum von ¹⁴C wird aufgezeigt. Bei der Bestimmung von Tritium lÄ\t sich der Quencheffekt nicht kompensieren, denn das Energiespektrum von Tritium wird durch eine Quenchverbindung anders beeinflu\t als das Spektrum von ¹⁴C bzw. ³⁵S.

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Summary After combustion of the organic sample a quenching effect is observed, due to several combustion products as NO₂, halogens, SO₂, and SO₃. We found, that it is possible to eliminate quenching of the combustion products in the determination of ¹⁴C and ³⁵S, if the high voltage of the data-photomultiplier is raised to a certain level (compensation point) and if the counting is performed in a window. The compensation point is calculated graphically by determining the counting rate of the pure absorbant and the absorbant plus the highest expected amount of combustion products. The relation between instrumental compensation and the energy spectrum of ¹⁴C is elucidated. It is not possible to compensate quenching in the determination of tritium, because the energy spectrum of ³H is influenced in a different way than the spectrum of ¹⁴C and ³⁵S.

     

Zur einfachen und schnellen Bestimmung von 3H, 14C und 35S in organischen Materialien

Ohne Zusammenfassung     

Production of 35S for a liquid semiconductor betavoltaic

The specific energy density from radioactive decay is five to six orders of magnitude greater than the specific energy density in conventional chemical battery and fuel cell technologies. We are currently investigating the use of liquid semiconductor based betavoltaics as a way to directly convert the energy of radioactive decay into electrical power and potentially avoid the radiation damage that occurs in solid state semiconductor devices due to non-ionizing energy loss. Sulfur-35 was selected as the isotope for the liquid semiconductor demonstrations because it can be produced in high specific activity and is chemically compatible with known liquid semiconductor media.     

Energy transfer processes in reactions of He(2 3S) and Ne(3P0,2) with CS2

A comparative spectroscopic study in the visible and ultraviolet ranges was conducted on the flowing afterglows resulting from the reactions of He(2 ³S) and Ne(³P_0,2) metastables with CS₂. Penning ionization was found to be the predominant energy transfer process. However, electron—ion recombination within the afterglows constitutes a major secondary process and gives rise to the most intense emitting system, CS(A ¹ Π → X ¹Σ⁺). Both afterglows were found to produce the CS⁺₂($\text{B}$²Σ⁺_u-$\text{X}$²Π_g), CS⁺₂($\text{A}$²Π_u-$\text{X}$²Π_g) and CS(a ³Π-X ¹Σ⁺) emission systems as well as some atomic sulfur emission lines. Some intensity differences were observed and are interpreted in terms of energetics and the formation mechanisms of the emitting species. A moderately strong CS⁺(A ²Π_i-X ²Σ⁺) emission system was also observed in the ehlium afterglow. In addition, a weak, sharp group of bands in the 390–420 nm range in the helium afterglow has been determined to be due to the presence of a small amount of He⁺ ions. This group of bands consists of two overlapping emission systems and are identified as CS(B ¹Σ⁺ → A ¹Π) and CS⁺(B ²Σ⁺ → A ²Π_i).     

The production of H(2S) atoms in the energy-transfer reaction of O2(1Δg) with HO2(X̃2A″)

The reaction of O₂(¹Δg) with HO₂(X?) was studied in an isothermal flow reactor in the pressure range 7?p? 10.7 mbar at temperatures between 299?T? 423 K. H-atom production was observed in the reaction O₂(¹Δg) + HO₂(òA′) - H(²S)+ 2O₂ (³Σ_g^?). The rate of this reaction (k₁) is estimated to be k₁ = (1 ± 0.5) × 10¹⁴ CM³ Mol^?1 s^?1. The implications of this reaction to recent determinations of the rate of the reaction H + O₂(¹Δg) are discussed.     

Die Trennung von 35S, 32P und 36Cl als Sulfat, Phosphat bzw. Chlorid an Aluminiumoxid

Ohne Zusammenfassung     

Energy-transfer reactions between He(2 3S) and Ne(3P0.2) metastable atoms and PN radicals

Energy-transfer reactions between He(2 ³S) and Ne(³P_0.2) metastable atoms and PN radicals have been investigated by emission spectroscopy. Thirteen new PN⁺ (B ¹Σ⁺ ?X ²Σ⁺) emission bands were found in addition to eight previously identified bands in the range 305–395 nm. From these observed band-head wavelengths, the following molecular constants were obtained for the X and B states of PN⁺ : PN⁺ (X): ω_c = 1306 ± 3 cm^?1, ω_cx_c = 7.9 ± 0.7 cm^?1, PN^? (B): T_c = 31354 ± 6 cm^?1, ω_c = 719 ± 3 cm^?1, ω_cx_c = 1.6 ± 0.7 cm^?1. The PN⁺ (B) state vibrational population was estimated from the emission intensities and the calculated Morse Franck—Condon (FC) factors for the PN⁺ (B–X) transition. Both the results obtained by He(2 ³S) and Ne(³P_0.2) Penning ionization shifted to lower vibrational levels in comparison with the calculated FC factors for vertical PN(X) → PN⁺ (B) ionization. Besides PN⁺ (B–X) emission, unidentified bands were observed in the 231–236 nm region in the helium afterglow, probably originating from PN or PN^?.     

Radiometric trace analysis of cobalt with diethyldithiocarbamate-35S,or 203Hg

Two radiometric methods for the determination of submugram amounts of cobalt are described. (A) Cobalt is extracted from an ammoniacal solution with a zinc-diethyldithiocarbamate-³⁵S solution in chloroform. Excess reagent and interfering metals are removed with mercury(II) and cyanide. The ³⁵S in the final organic layer is a measure of the cobalt in this layer. (B) Cobalt is extracted from an ammoniacal solution with a fixed amount of zinc-DDC in chloroform. Excess reagent and complexes of foreign metals are removed by exchange with ²⁰³Hg⁺² and the ²⁰³Hg in the chloroform (compared with a blank) acts as a measure of the cobalt. Method A is applicable to 0.1 μg of cobalt and method B to 0.8 μg. As the efficiency of both processes is variable, isotope dilution with ⁶⁰Co is carried out, A 10-fold excess of foreign metals is permitted in method A and a 4-fold excess in method B ; larger amounts are previously removed, e.g. by extraction with inactive zinc-DDC from sodium hydroxide media.     

Physical and chemical forms of radionuclides of 38S, 38Cl, 39Cl, and 82Br, produced at a high-energy proton accelerator facility

High-energy protons and neutrons produce various radionuclides in the air, mainly through the nuclear spallation of atmospheric elements. Air samples were collected from the EP-2 tunnel of the KEK 12 GeV proton synchrotron facility with a filter pack, which consisted of a membrane filter for aerosols, a Na₂CO₃-impregnated filter for acidic gases, and an activated carbon fiber filter for non-acidic gases. Sulfur-38 was found on the membrane and Na₂CO₃-impregnated filters, ³⁸Cl and ³⁹Cl were on the membrane, Na₂CO₃-impregnated, and ACF filters, and ⁸²Br was only on the ACF filter. The results on the relative abundances of aerosol and gaseous acidic components have indicated that ³⁸Cl produced by thermal neutron capture, which is the main reaction for ³⁸Cl production in the EP-2 tunnel air, are likely not to be present as aerosol or acidic gas. This was similar to the case of ⁸²Br produced by thermal neutron capture.     

Rate constants for O(3P) recombination and association with N(4S)

It is shown that N(⁴S) and O(³P) atom quenching effects upon chemiluminescence from NO(B²π) (θ = 0) are of importance when this emissio Values of k₂ = (1.74 ± 0.13) × 10⁹ and (4.05 ± 0.17) × 10⁹ &² mole^-2 sec^-1 are found at 298 and 196°K respectiv