Progress of laser spectroscopy at the IGISOL

Magnetic interactions and microstructure in the amorphous and nanocrystalline Fe₉₀Zr₇Cu₁B₂ alloy were investigated. These studies were carried out in the temperature range from 140 up to 380 K, using a Mössbauer spectrometer and completely automated set-up for measurements of magnetic properties. It has been found that the Curie temperature and quadrupole splitting decrease after annealing the sample at 573 K for 1 h (invar effect). However, this behaviour is not observed in nanocrystalline samples. In the early stages of crystallization (the volume fraction of the crystalline phase equal to about 0.06) α-Fe grains above the Curie temperature of amorphous matrix may be treated as non-interacting particles. The particle size estimated by Mössbauer spectra and magnetization curve analysis is equal to about 4 nm.     

Consistency requirements for 1N expandable field theories

It is demonstrated that $\text{1}\text{N}$ expansion in a class of field theories with an internal O(N) symmetry leads to pathologies. Therefore, these models are either not internally consistent, or their perturbation expansions (ordinary as well as $\text{1}\text{N}$ are unreliable.     

Defects and diffusion in MnO

Diffusional transport of manganese through MnO scales has been studied at temperatures from 900–1200°C by means of a novel diffusion/evaporation method and by the two-stage oxidation (Rosenburg) method. In the phase field of Mn_1?vO near the MnO₃O₄ phase boundary the manganese self-diffusion coefficient and the concentration of defects is concluded to be proportional to . The concentration of defects increases with decreasing temperature at constant partial pressure of oxygen. In this non-stoichiometry range Mn_1?yO has properties similar to wüstite, Fe_1?yO, and it is concluded that the important cation defects are defect clusters. The results may be explained assuming that the defect clusters consist of four vacancies on octahedral sites and one interstitial on a tetrahedral site. Values for the concentration of defects, the self-diffusion of manganese ions and of the defects have been calculated. For the phase field near the M/MnO phase boundary it is concluded that Mn-interstitials predominate.     

A scheme for automatic generation of boundary-fitted depth- and depth-gradient- dependent grids in arbitrary two-dimensional regions

In this paper we present a scheme for the numerical generation of boundary-fitted grids that adapt to both water depth and depth gradient. The scheme can be used in arbitrary two-dimensional regions and is based on the application of the well-known control function approach to generate adaptive grids. The method includes the evaluation of water depths at the grid points from a known distribution of depth points and their associated depths plus a procedure for the numerical evaluation of depth gradients. It is demonstrated that the smoothness of the grid can be enhanced by introducing a suitable filtering technique.     

Determination of some atomic-state densities in an Xe-Br2 mixture

The atomic-state densities of the 6s[1 $\text{1}\text{2}$]⁰ metastable Xe energy level and of the 5s⁴P_{$\text{1}\text{2}$}, 5s⁴P_{$\text{3}\text{2}$} and 5s⁴P_{$\text{5}\text{2}$}Br energy levels in an Xe-Br₂ mixture have been determined as a function of current strength.     

Multiple substitution effects in configuration interaction calculations

The common way of approximating multiple substitution effects by the unlinked cluster contribution based on the linked cluster theorem is investigated. Formally the analysis is done in a configuration interaction language without reference to diagrams. Using the linked cluster theorem a series expansion is then developed for the correction of a CI calculation, including double replacements only, for the erratic treatment of unlinked clusters. The first term in this series is closely related to what is generally referred to as Davidson's correction. The next term is proportional to the square of the correlation energy and is also very easy to calculate. Finally numerical examples are given illustrating the accuracy of the different approximations.     

Acyl thiocyanates—III: The synthesis of stable Aroyl thiocyanates

Two methods are devised for the synthesis of aroyl thiocyanates. One method is based on the thermal breakdown of 5-aroylthio-1,2,3,4-thiatriazoles to aroyl thiocyanates, nitrogen and sulfur. The other method is based on the reaction between thioacid salts and cyanogen halides. The latter synthesis also gives rise to diacyldisulfides. A hypothesis for the disulfide formation is advanced. These investigations have revealed that 2,4,6-tribromobenzoyl- and 2,4,6-tridobenzoyl thiocyanate are stable compounds which can be kept at room temperature for prolonged periods without decomposition, while 2,6-dimethyl-4-nitrobenzoyl and 3,4,5-trimethoxybenzoyl thiocyanate are of intermediate stability. The former thiocyanates are the first examples of stable acyl thiocyanates.     

On the determination of an orthogonal transformation

Let A and B be n × m-matrices with m >- n. An iterative algorithm for the determination of the orthogonal P minimizing /vbPA - B /vb_F² is suggested and analyzed. Convergence is proved under natural assumptions.