The dependence of the intensity of the bremsstrahlung and the characteristic X-radiation induced by a beta-emitting14C-isotope was investigated as a function of the layer thickness and the atomic number of the absorbent. The theoretically
calculated and measured values of layer thickness required for maximum radiation intensity were in good agreement. The atomic
number values required for maximum bremsstrahlung and characteristic radiation were ascertained. The obtained extreme values
were attributed to a resonance effect occurring by the interaction of β-particles with theK electrons of the absorbent.
The analytical application of the measurement of the absorption of the characteristic X-radiation, induced in various targets
by means of a β-source, has been investigated. With properly selected targest exploiting the phenomenon of resonance absorption,
the composition of solutions and mixtures can easily be determined with an accuracy of 1–2 relative per cent.
Besides -Sn, a Ni–Sn alloy was identified by means of Mössbauer investigations on tin plated nickel foils formed during the electrodeposition of119Sn on nickel substrate. The average thickness of the layer caused by electroimplantation is about 80 to 100 nm on each side of the sample. The amount of the Ni–Sn alloy increases by heat treatment and the activation energy of the interdiffusion Q=102.5±2 kJ/mol was determined. A diffusion into the substrate could not be observed for electrodeposited119Sn on aluminium even at temperatures above the melting point of tin.
During electrodeposition of Sn on Ag substrate an interphase formation /electroimplantation/ could be observed. The average thickness of the formed alloy amounts to 35 nm. Heat treatment increases the thickness of the interphase, the activation energy of the interdiffusion process is 45.5±2 kJ mol–1. The system Sn on Pt substrate showed no electroimplantation. The diffusion during heat treatment has an activation energy of 126.2±2 kJ mol–1. Isomer shift of the formed alloys indicates that Pt diffuses preferentially into the tin layer.
Anomalous temperature dependent changes were found in 2-1-2-2 Type Tl-containing high temperature superconductor around the TC1. The anomaly can be interpreted as relaxation changes due to Cooper pairing with energy predicted by the BCS theory.
Calculations were performed on a model of multicomponent, fine-grained materials to simulate positron distributions immediately after the thermalization process. A real three-component system (-Ni(OH)2/-NiOOH/graphite) was fitted by the parameters of the model and positron lifetime parameters were determined for the interfaces of the system.
Authors:E. Kuzmann, M. Gál, Cs. Vértes, and A. Vértes
57Fe Mössbauer measurements were performed on FeSO3 being in frozen solution and in crystalline states. The obtained typical Mössbauer parameters for crystalline FeSO3.3H2O are IS=1.23±0.05 mm s–1 and QS=2.50±0.01 mm s–1, while for the fozen solution: IS=1.32±0.01 mm s–1, QS=3.24±0.01 mm s–1. It show that FeII is hexaaquacoordinated in the solution.
The most obvious symmetry breaking in Nature is the left-right asymmetry of living beings: sugars and amino acids are almost exclusively represented by one of their stereoisomers (D-isomer for sugars and L-isomer for amino acids) at the expense of other possible isomers. In our experiment we studied the aqueous solutions of tartaric acid, alanine, and cysteine in the function of temperature by positron lifetime spectroscopy. The results were compared with those obtained in pure water under similar conditions. We always observed a sharp minimum of the positron lifetime at around 41 °C in water and in the solutions of the natural stereo-isomers. On the other hand, the same minimum occurred at considerably lower temperatures in the solutions of the unnatural isomers.