Raman and Infrared Spectroscopic Study of the Borate Mineral Kaliborite

We have studied the mineral kaliborite. The sample originated from the Inder B deposit, Atyrau Province, Kazakhstan, and is part of the collection of the Geology Department of the Federal University of Ouro Preto, Minas Gerais, Brazil. The mineral is characterized by a single intense Raman band at 756 cm^?1 assigned to the symmetric stretching modes of trigonal boron. Raman bands at 1229 and 1309 cm^?1 are assigned to hydroxyl in-plane bending modes of boron hydroxyl units. Raman bands are resolved at 2929, 3041, 3133, 3172, 3202, 3245, 3336, 3398, and 3517 cm^?1. These Raman bands are assigned to water stretching vibrations. A very intense sharp Raman band at 3597 cm^?1 with a shoulder band at 3590 cm^?1 is assigned to the stretching vibration of the hydroxyl units. The Raman data are complimented with infrared data and compared with the spectrum of kaliborite downloaded from the Arizona State University database. Differences are noted between the spectrum obtained in this work and that from the Arizona State University database. This research shows that minerals stored in a museum mineral collection age with time. Vibrational spectroscopy enhances our knowledge of the molecular structure of kaliborite.     

In-line and following-up tests of perspective fusion-reactor materials in plasma focus devices

The paper presents results of recent experiments, as performed with the PF-1000 and PF-6 Plasma-Focus facilities, which were aimed at investigation of the correlation between processes of the irradiation of different materials of fusion devices and results of this irradiation. Among the irradiated samples there were pure tungsten, tantalum, copper, aluminum, and alloys, based on these metals, various steels, carbon and carbon-based materials, which are designed for plasma facing components or constructional parts of future thermonuclear reactors of the inertial- and magnetic-confinement types. The corpuscular radiation consisted of high-energy (E _D>100 keV) deuterium ion beams and fast (v _str ≥ 10⁷ cm/s) deuterium-plasma streams. They were investigated by a number of methods with spatial and temporal resolution. Particular attention was paid to the verification of diagnostic techniques, which might be used for time- and space-resolved studies of the interaction process. Correlation of these data with information obtained from subsequent analytical investigation of some of the irradiated specimens, as performed by means of a number of methods typical for material sciences, gives possibility to deduce physical mechanisms of the deuterium implantation and radiation damage of the investigated materials in dependence on the conditions of their irradiation.     

Anomalous temperature dependence of the magnetic hyperfine field of99Ru in gadolinium

The magnetic hyperfine field at dilute⁹⁹Ru impurities in ferromagnetic Gd has been investigated as a function of temperature by time differential perturbed angular correlation (TDPAC) measurements. The saturation field at 11 K is H_hf(Ru Gd)=51(2) KOe. This value fits well into the systematics of 4d impurity hyperfine fields in Gd. The magnetic hyperfine field of RuGd does not follow the magnetization of the host (T_c=290 K) but vanishes abruptly at about 70 K. A similar behaviour has previously been observed for the 5d impurity Os in Gd. From first TDPAC measurements of the hyperfine interactions in the intermetallic phases of the Ru-Sc system it can not be completely ruled out that the observed collapse of the hyperfine field at 70 K is due to the formation of the intermetallic compound RuGd₃.This work has been supported by the Minister für Wissenschaft und Forschung des Landes Nordrhein-Westfalen     

Coulomb and nuclear excitation in the sequential break-up of6Li

The dissociation of⁶Li in the field of²⁰⁸Pb has been measured above the Coulomb barrier along with the elastic scattering. The inelastic angular distributions showing typical Coulomb nuclear interference structure can be very well reproduced by refined optical model calculations.     

Frenkel exciton model of electron energy loss spectroscopy in -PTCDA

Recent experimental findings concerning electron energy loss spectroscopy in -Perylene-tetracarboxylic-dianhydride are analysed in terms of a Frenkel exciton model. Taking into account the energy dispersion of excitations with finite momentum transfer, the k-dependence of the dielectric tensor and the corresponding electron energy loss functions can be calculated. The exciton dispersion with a minimum at k≠0 yields a red shift of the lineshape of loss functions at large k, as observed experimentally.     

SCF-Xα-SW-Berechnungen kleiner Si-F-Verbindungen

SCF-X_αSW Calculations of Small Si-F Compounds SCF-X_α-SW calculations have been used to compare the bonding situations between the tetrahedral SiF₄ molecule (T_d), the hexafluorosilicate anion SiF₆^2? (O_h), and the hypothetical planar SiF₄ molecule (D_4h). The size of the atomic spheres has been determined using both the covalent atomic radii of Slater [11] and the charge and atomic number radii according to Norman [12]. The molecular orbital analysis has been performed for the valence levels of the three molecules and the charge distributions have been calculated. Ab initio-3-21G calculations have been carried out to optimize the bond lengths of the Si-F species and to compare the results with former performed CNDO/2 calculations.