DISPA method in the analysis of Mössbauer spectra of metallic glasses

A plot of the DISPersion mode of a pure, ideal Lorentzian line versus the Absorption one (DISPA plot) gives a perfect circle. Non-Lorentzian profiles distort this reference circle in an unambiguous way. A modification of the DISPA method for the lineshape analysis of Mössbauer spectra of amorphous Fe₈₃B₁₇ and Fe₄₀Ni₄₀B₂₀ pointed out convolutions of Gaussian and Lorentzian lines to be somewhat superior. Based on the previous results a construction of a hyperfine field distribution is proposed.     

Effect of Ti pretreatment on photoelectric properties of TiO2 layers prepared by plasma-anodic oxidation

Photoactive TiO₂ layers were formed by anodic oxidation of Ti in O₂ RF plasma under various conditions and Ti surface pretreatment. The photocurrent spectrum in 1M NaOH was used to calculate the quantum efficiency of the photocurrent production and the band-gap energy for indirect transitions. Photoelectrochemical properties of TiO₂ layers were studied on the decomposition of p-cresol water solution. The method of Ti surface pretreatment (mechanical polishing or chemical etching) has a decisive influence on the photoelectrochemical properties and the structure of the polycrystalline oxide, rutile, anatase or amorphous phase content.This study was supported by the Grant Agency for Sciences of Slovakia.     

Cycloaddition of diazomethane to unsymmetrical carbodiimides and mass spectroscopy study of 1,5-disubstituted 1,2,3-Triazoles

By the reaction of unsymmetrically substituted carbodiimides with diazomethane the corresponding 1,2,3-triazoles have been obtained. The structure of the adducts was elucidated by IR, UV,¹H-NMR and high resolution mass spectrometry.

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Cycloaddition von Diazomethan an unsymmetrische Carbodiimide und massenspektroskopische Studien an 1,5-disubstituierten 1,2,3-Triazolen

Zusammenfassung Die Struktur der aus unsymmetrischen Carbodiimiden und Diazomethan gebildeten 1,2,3-Triazolen wurde durch IR-,UV-,¹H-NMR- und Massenspektrometrie aufgeklärt.

     

On art,science, beauty and the experimentalist

Comments are made on the concepts of beauty and art, and their relationship with physical phenomena. Experimental physicists have means at their disposal to produce objects of art just as the painter uses oil and the sculptor uses marble to produce objects of art. Several new photographs of “log-art” or artistic science are shown.     

Intrinsic Josephson junctions in Bi2Sr2CaCu2O8+δ single crystals

We report on thec-axis superconducting energy gap parameter Δ _c (T) of intrinsic Josephson tunnel junctions inBi ₂ Sr ₂ CaCu ₂ O _8+δ (Bi2212) single crystals. Δ _c (4.2K)≈10−13 meV, which is approximately a factor of two smaller than reported in the majority of tunneling experiments. Δ _c (T) deviates strongly from the BCS temperature dependence. These observations may be explained by a multilayer model of Bi2212 which assumes that theBi−O layers are superconducting due to the proximity effects. The Josephson tunneling then takes place between adjacentBi−O layers while there is a strong proximity coupling betweenBi−O andCu−O layers. The work is supported by Swedish Supercon-ductivity Consortium and NUTEK, and, in part, by Russian Foundation for Basic Research, grant #95-02-04307     

A fast algorithm for repeated computation of linear recurrence relations

Let the calculation of thenth term of a general recurrence relation requireO(q(n)) arithmetical operations. The derivation is given of a new algorithm that performsm repetitions of this calculation with different initial conditions requiring onlyO(q(n)) +O(m) operations. The application of this algorithm to accelerate the calculation of continued fractions and the solution of three- and five-diagonal systems of linear equations, is also described.     

Effect of immobilizing adsorption on mass transport through polymer films

The Freundlich isotherm used in place of the Langmuir isotherm to describe the adsorption mode in the dual sorption theory of glassy polymer—gas systems. Time-lag expressions have been derived and compared with the available corresponding results for the Langmuir case. In the case of large and moderate values of the upstream boundary activity a₀, the value of the time-lag function L^a)(l) calculated with the proposed model is close to that calculated by Paul for the Langmuir isotherm. In the case of small values of a₀, the L^a(l) values predicted by Paul and the proposed model are different and the difference increases when the value of a₀ decreases. The ability of the present model to represent systems exhibiting positive deviations from Henry's law is also described.