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Abstract  

Photolytic products of tetramethylstannane in low temperature argon matrix were studied by Mössbauer, IR, and UV spectroscopy. At an early stage of the reaction, an unstable tin compound possibly with a tin-carbon double bond was formed in low temperature argon matrix, which might not exist in ordinary conditions. In subsequent reaction, cyclic tin compounds with large quadrupole splittings might be produced.

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Abstract  

Mass Spectrometry has been the usual method to determine Ar concentrations in mineral samples for dating them through the40Ar/40K ratio. This technique has been replaced since 1966 by measurement of40Ar/39Ar ratio, after artificial production of39Ar from the39K(n,p)39Ar reaction produced in the fast neutron flux of a nuclear reactor. This method requires the fusion of the sample by incremental heating until reaching a temperature of 1000°C in order to get the total release of both argon isotopes. In principle, it should be possible to determine the40Ar/40K ratio by activation analysis in an easier, non-destructive way, but it presents the following drawbacks: manufacture of argon standards; usual low ratio peak/Compton distribution for both peaks: 1.29 Mev and 1.52 Mev (41Ar and42K respectively), since potassium minerals are usually very rich in sodium, manganese and chlorine; reaction41K(n,p)41Ar induced by fast neutrons present in the thermal flux; and possible contamination of the samples and standards with atmospheric40Ar (99.6% of elementary Ar, whose proportion in the atmosphere at sea level is 0.93%). This paper describes how these problems may be solved, also determining the limits of Ar and K concentration related to Compton distribution, in our experimental conditions.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Wang, S. Tokiwa, T. Nishide, Y. Kasahara, S. Seki, T. Uchida, M. Ohtsuka, T. Kondo, and Y. Sawada

Abstract  

Amorphous indium-tin-oxide (ITO) transparent conducting film (15 at% Sn; thickness, 150–190 nm) was deposited on silicon wafer at room temperature by RF magnetron sputtering for temperature programmed desorption (TPD) in vacuum. The thermal crystallization was accompanied by evolution of water vapor (the main gas), argon and carbon dioxide. The total amount of evolved water vapor (H2O [mol]/(In [mol]+Sn [mol])>0.2) was one or two orders of magnitude more than that from the nanocrystalline ITO films reported in our previous papers. The thermal change of amorphous ITO film was remarkably affected by the position of the substrate. An abrupt gas evolution was characteristic of the amorphous ITO films deposited on the position near the target center. The evolution temperature (548–563 K) was higher than the gas evolution temperature from the crystalline films. The far from center positioned films crystallized at higher temperature with relatively slower evolution of the gases.

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The adsorption of argon, oxygen, nitrogen and carbon monoxide at 77 K on crystalline zirconia and microporous zirconia gels has been studied by adsorption volumetry and isothermal microcalorimetry.

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Abstract  

Unusually broad119Sn-Mössbauer absorption was observed in pure Sn(CH3)4 or Sn(CH3)4/argon condensed at low temperatures by pulsed deposition. Such broadening of the Mössbauer linewidth suggested the presence of large quadrupole splitting due to possible distortion of molecular structure as deposited in the argon matrix.

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Abstract  

Argon ion induced X-ray emission has been used for analysis of Si and Cl present at low concentrations in CdTe crystals. The influence of zone melting on the distribution of these elements along the crystal is examined.

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Abstract  

A new method for the preparation of Tc metal from pertechnetate is described. Metallic technetium was prepared from TcO4 by initial reduction in dry argon atmosphere at 300 °C followed by a wet argon atmosphere in the presence of carbon between 700 and 910 °C. The higher temperature conditions in the presence of H2O and carbon form H2 and CO, which can drive the reduction of TcO2. This method was applied to the recovery of pertechnetate sorbed on anion-exchange resins resulting in the formation of Tc metal microspheres. The resulting Tc was characterized by XRD analysis and SEM.

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Abstract  

Yields of Fe3+ from aerated and deaerated solutions of ferrous sulfate irradiated with high energy carbon or neon ions are shown to be consistent with current theoretical models of radiation chemistry, if fragmentation of the incident ion is taken into account. For argon, the observed yields are higher than predicted.

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Abstract  

An instrumental procedure for the determination of the amount and the radio-activity of argon, krypton and xenon has been worked out and an automatic analyser has been designed. A sample was taken from the residual gases remaining after absorption in a solution of potassium hydroxide. Oxygen was catalytically combusted and carbon monoxide converted to methane in a stream of hydrogen. Argon and krypton were separated on a 5.5 m long column packed with Porapak Q, and xenon was analyzed on a 0.4 m long column of Synachrom G-5 at 0°. The radioactivity of the pure components was measured with a flow-type proportional counter. The system proposed and the analyser can be simply adapted to run off determinations of other admixtures in the coolants of nuclear power plants.

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Radiation effects in the transient hot-wire technique

Measurement of the thermal conductivity of n -pentane

Journal of Thermal Analysis and Calorimetry
Authors: Y. Shi, L. Sun, J. Venart, and R. Prasad

Abstract  

The transient hot-wire technique is widely used for absolute measurements of the thermal conductivity and thermal diffusivity of fluids. It is well established that fluid radiation effects significantly influence these measurements, especially those for the thermal diffusivity. Corrections for radiation effects are based on the models developed and deviations of the measured data from the ideal line source model. In this paper, the effect of fluid radiation on the measurements of the thermal conductivity of n-pentane is presented. For comparison, the influence of thermal radiation effect on measurement of transparent fluids, such as argon is also shown. The difference between the influence of natural convection and thermal radiation is also demonstrated.

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