Studies of LA-ICP-MS on quartz glasses at different wavelengths of a Nd:YAG laser

The capability of LA-ICP-MS for determination of trace impurities in transparent quartz glasses was investigated. Due to low or completely lacking absorption of laser radiation, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) proves difficult on transparent solids, and in particular the quantification of measurement results is problematic in these circumstances. Quartz glass reference materials of various compositions were studied by using a Nd:YAG laser system with focused laser radiation of wavelengths of 1064 nm, 532 nm and 266 nm, and an ICP-QMS (Elan 6000, Perkin Elmer). The influence of ICP and laser ablation conditions in the analysis of quartz glasses of different compositions was investigated, with the laser power density in the region of interaction between laser radiation and solid surface determining the ablation process. The trace element concentration was determined via calibration curves recorded with the aid of quartz glass reference materials. Under optimized measuring conditions the correlation coefficients of the calibration curves are in the range of 0.9-1. The relative sensitivity factors of the trace elements determined in the quartz glass matrix are 0.1-10 for most of the trace elements studied by LA-ICP-MS. The detection limits of the trace elements in quartz glass are in the low ng/g to pg/g range.     

Lifetime measurements and decay of superdeformed bands in Hg isotopes

The lifetimes of states in Superdeformed (SD) bands in ^192,194Hg have been measured using the Doppler shift attenuation method. Intrinsic quadrupole moments have been extracted for band 1 of ¹⁹²Hg and for bands 1, 2, and 3 of ¹⁹⁴Hg. It was found that the quadrupole moments for the “identical” SD bands in these nuclei are the same. In the same experiment, one-step transitions linking SD states to yrast and near yrast states for bands 1 and 3 of ¹⁹⁴Hg have been identified. From this observation, excitation energies, spins and probable parities have been assigned to SD states in these bands.     

Supersymmetry breaking,heterotic strings and fluxes

In this paper we consider compactifications of heterotic strings in the presence of background flux. The background metric is a T² fibration over a K3 base times four-dimensional Minkowski space. Depending on the choice of three-form flux different amounts of supersymmetry are preserved (N=2,1,0$N=2,1,0$). For supersymmetric solutions unbroken space–time supersymmetry determines all background fields except one scalar function which is related to the dilaton. The heterotic Bianchi identity gives rise to a differential equation for the dilaton which we discuss in detail for solutions preserving an N=2$N=2$ supersymmetry. In this case the differential equation is of Laplace type and as a result the solvability is guaranteed.     

Optical Method for the in-situ Measurement of the pH-value During High Pressure Treatment of Foods

This contribution presents a novel optical method to determine the pH-value during the high pressure treatment of foods. Up to date an appropriate online measurement device does not exist. The present study makes use of a multivariate approach, using the optical properties of pH indicators. An indicator mix of 16 different pH-sensitive substances is applied. The calibration of the system is performed taking five different buffer substances (TRIS, CAPS, citric, phosphoric and acetic acid buffers), applying thermodynamical considerations, to calculate the pH-value at high pressure. The corresponding spectra of the indicator mix is measured and fed to a multivariate data model together with calculated pH values. Different chemometric models have been constructed to estimate the pH value based upon the spectrum of the indicator mix. The calibration device covers a pH range from 2 to 8. After calibration it was possible to determine the pH value at pressures up to 450 MPa with an accuracy of 0.02 pH units in 9 different test media.     

Observation of superdeformed bands in194Hg

Two rotational bands, with energy spacings characteristic of superdeformed shapes, have been observed following bombardment of¹⁵⁰Nd with⁴⁸Ca. The more intensively populated band consists of 18 transitions and is assigned to¹⁹⁴Hg. The depopulation of this band occurs around spin 10. The second band, consisting of at least 16 transitions, was populated less strongly and is tentatively assigned to¹⁹⁴Hg also. The lowest level in this band is assigned spin 8. The energy differences between transitions for both bands decrease from ～40 keV at low rotational frequencies to ～30 keV at the highest observed frequencies. The moments of inertia of the bands are similar to those of the two previously observed superdeformed bands in^191,192Hg. The similarities and differences of the four known bands in the mercury region are discussed.     

Tetra­ethyl­ammonium bis­(N,N‐diethyl­dithio­carbamato‐κ2S,S′)iodo­cadmate(II)

The title compound, (C₈H₂₀N)[Cd(C₅H₁₀NS₂)₂I], containing a heteroleptic five‐coordinate mononuclear anionic cadmium complex, crystallizes in ortho­rhom­bic form in the space group Pnma. Both anion and cation lie about mirror planes. Unlike other known [Cd(dtc)₂X]‐type complexes (where dtc is dithio­carbamate and X is a halogen or pseudohalogen), the central CdS₄I core shows a square‐pyramidal configuration, with a basal plane defined by four S atoms from two chelating dithio­carbamate ligands related by a symmetry plane. The central Cd atom is displaced from the basal S₄ plane towards the apical I atom of the square pyramid.     

Bildung und Eigenschaften von Aoylphosphinen. III. Molekül- und KristallStruktur von Dipivaloylphosphin

Syntheses and Properties of Acylphosphines. III. Molecular and Crystal Structure of Dipivaloylphosphine In the reaction of tris(trimethylsilyl)phosphine with pivaloyl chloride two Si? P bonds are cleaved and dipivaloyltrimethylsilylphosphine is formed. Reaction with methanol yields dipivaloylphosphine. N.m.r. investigations show a tautomeric equilibrium between keto and enol form as in β-diketones. The substance crystallizes in the orthorhombic space group Pmmn with molecules in two crystallographically different sites [cell parameters: a = 14.04(1), b = 13.82(1), c = 6.28(2) Å]. An X-ray structure determination (R = 5.0%) proves the existence of the enol form in the solid, in that (1.) the molecular symmetry is mm 2(C_2v), (2.) P? C bonds are shortened and C? O bonds are elongated, and (3.) we find a symmetric hydrogen bridge with a very short O? O distance. Bond lengths and angles are compared with those of other β-diketones. The packing of molecules is studied in detail.     

Heavy-ion transfer reactions on 208Pb above the coulomb barrier

The selective excitation of single-particle and hole states in stripping and pick-up reactions induced by ¹¹B ions of 113.5 MeV on ²⁰⁸Pb is interpreted on the basis of a semi-classical theory. The excitations of outgoing ions and the continuum are also discussed.