Determination of traces of carbon, nitrogen and oxygen in molybdenum and tungsten

The determination of carbon and nitrogen in molybdenum and of carbon, nitrogen and oxygen in tungsten, is described. The analytical techniques applied were charged-particle activation (carbon, nitrogen and oxygen), photon activation (carbon and oxygen), combustion (carbon) and vacuum-fusion extraction (nitrogen and oxygen). Chemical methods yielded upper limits in the 2-5 mug/g range. Activation analysis yielded 100 and 8 ng/g for carbon in molybdenum and tungsten respectively, 500 and 74 ng/g for nitrogen in molybdenum and tungsten respectively and 70 ng/g for oxygen in tungsten. The results obtained by charged-particle and photon activation agreed satisfactorily.     

Darstellung und Struktur der Tetrafluoroaurate(III) MI[AuF4] mit MI = Li,Rb

Synthesis and Structure of Tetrafluoroaurates(III) M^I[AuF₄] with M^I = Li, Rb Single crystal investigations on Rb[AuF₄], light yellow, confirm the tetragonal unit cell (K[BrF₄]-type) with a = 618.2(1) and c = 1191(1) pm, Z = 4, space group I 4/mcm-D (No. 140). Li[AuF₄], light yellow too, crystallizes monoclinic with a = 485.32(7), b = 634.29(8), c = 1004.43(13) pm, β = 92.759(12), Z = 4; space group P 2/c-C (No. 13). The structure of Li[AuF₄] is related to the Rb[AuF₄]-type of structure.     

Measurement of the\sum {^ - \to ne^ - \bar v} rate and search for ΔQ=−ΔS transitions in Σ+→ne + ν decay

In a bubble chamber experiment about 2×10⁶ Σ ^±-decays have been measured to separateΣ ^±→ne^±¯ν events from the two-body modes. NoΣ ⁺ →ne ⁺ ν event was found whereas 607Σ ^?→ne^?¯ν decays could be identified. The data yield for the ΔQ=?ΔS decay an upper limit: $$\frac{{\Gamma \left( {\sum {^ + } \to ne^ + v} \right)}}{{\Gamma \left( {\sum {^ - } \to ne^ - v} \right)}}< 1.9 x 10^{ - 2} (90\% confidence level)$$ and the branching ratio: $$\frac{{\Gamma \left( {\sum {^ - } \to ne^ - v} \right)}}{{\Gamma \left( {\sum {^ - } \to n\pi ^ - } \right)}} = (1.09 \pm 0.06) x 10^{ - 3} .$$      

Two-level primal-dual decomposition technique for large-scale nonconvex optimization problems with constraints

A two-level decomposition method for nonconvex separable optimization problems with additional local constraints of general inequality type is presented and thoroughly analyzed in the paper. The method is of primal-dual type, based on an augmentation of the Lagrange function. Previous methods of this type were in fact three-level, with adjustment of the Lagrange multipliers at one of the levels. This level is eliminated in the present approach by replacing the multipliers by a formula depending only on primal variables and Kuhn-Tucker multipliers for the local constraints. The primal variables and the Kuhn-Tucker multipliers are together the higher-level variables, which are updated simultaneously. Algorithms for this updating are proposed in the paper, together with their convergence analysis, which gives also indications on how to choose penalty coefficients of the augmented Lagrangian. Finally, numerical examples are presented.     

Transmission of spin—spin coupling constants through different paths in bicyclo(2,2,1)heptane: their calculation using inner projections of the polarization propagator

Inner projections of the polarization propagator are used to calculate components of the Fermi contact interaction between protons attached to the bridgehead carbon atoms of bicyclo(2,2,1)Heptane. Four- and five-bond paths and throuh-space interaction are considered. Reasonable path additivity and agreement with experimental data are found at the INDO level.     

Influence of the INDO parameterization on the indirect spin–spin coupling constants as calculated by the FPT INDO method

Alterations have been introduced in the semi-empirical INDO parameters in order to study their influence on the Fermi contact term of the indirect spin–spin coupling constants as calculated by the finite perturbation theory (FPT). For this purpose a set of molecules containing hydrogen, carbon and/or fluorine has been selected. In general, most coupling constants are found to be much more sensitive than other molecular properties to small changes in the INDO parameters. This sensitivity depends strongly on the particular calculated coupling constant. In most cases the uncertainty in the INDO parameters leads to uncertainties in the coupling constants which are much greater than their experimental errors.     

The application of low energy ion scattering spectroscopy (LEIS) in sub 28‐nm CMOS technology

With the transition to ≤28‐nm CMOS technology nodes, the surface analytical challenges with regard to steadily decreasing dimensions and still growing materials options raise the demand of high performing surface analysis techniques. Characterization of ultrathin films and multilayer stacks, especially in high‐k metal gate stacks, by means of low energy ion scattering spectroscopy (LEIS) with its monolayer sensitivity has been established as a very useful analysis technique next to Auger electron spectroscopy, X‐ray photoelectron spectroscopy , and time‐of‐flight secondary ion mass spectrometry. Questions regarding film nucleation, growth, coverage, and diffusion can be answered, thereby enabling those processes to be controlled appropriately. In this work, growth studies of ALD HfO₂ and TiN are shown, as well as film thickness determination based on surface spectra. PVD aluminum and lanthanum, acting as work function metals on the gate oxide, were deposited, and their film formation and closure were investigated. Further application fields of LEIS have emerged from the characterization of in‐die features on patterned wafers. As presented on test arrays, it is possible to detect material deep in trenches. This is an advantage if residues need to be identified after etch or clean processes.