Influence of surface structure on surface analytical statements

The influence of surface structure of technical materials on results and statements of surface analytical methods has been investigated. Especially surface roughness as a typical property of rolled products has been observed. For this purpose samples of steel (technical surface, roughness up to 5 m) and silicon wafers (polished surface) have been analyzed by SNMS and GDOS in order to get information about changes of the surface roughness as function of the sputtering time and their influence on the statements about the depth profiles obtained.     

Differential thermal analysis - evolved gas analysis of synthetic goethite

Samples of synthetic goethite have been studied by combined DTA-EGA. The total CO₂ content of the samples ranged between 1.0 and 2.7 %wt. The origin of the evolved CO₂ is discussed and it is proposed that the samples contain CO₂ as surface complexes and incorporated in the crystal structure.     

Darstellung und Reaktionen von Selenocarbonyldifluorid und seines cyclischen Dimeren 2,2,4,4-Tetrafluor-1,3-diselenetan [l]

Inhaltsübersicht. Das erstmals hergestellte B(SeCF₃)₃ zerfällt unter dem katalytischen Einfluß von Alkalifluoriden zu F₂C=Se und BF₃. In Anwesenheit von BF₃ polymerisiert F₂CSe bereits. bei ?;80°C. Oberhalb 150°C depolymerisiert (F₂CSe)_n wieder zu F₂C=Se und. Durch Halogenaddition an F₂C = Se gewinnt man F₂XCSeX (X = Cl, Br). Das in der Reihe Cl_3–nF_nCSeCl noch fehlende Cl₂FCSeCl wird durch Umsetzung von CSe₂, ClF und Cl₂ synthetisiert. F_nCl_3–nCSeCl (n = 1. 2) liefert mit Zinn die entsprechenden symmetrischen Diselane, mit AgCN die Selenocyanate. Durch Halogenaustausch mit BX₃ (X = Cl, Br) wird umgewandelt. XC(S)Cl reagiert mit Hg(SeCF₃)₂ zu CF₃SeC(S)X (X = F, Cl. CF₃Se). Daraus werden durch Chloraddition die entsprechenden Sulfenylchloride synthetisiert. IR-NMR- und Massenspektren der neu hergestellten Substanzen werden angegeben. Preparation and Reactions of SeCF₂ and its Cyclic Dimer 2,2,4,4-Tetrafluoro-1,3-diselenetane Abstract. B(SeCF₃)₃, prepared for the first time, decomposes under the influence of alkali metal fluorides to F₂C=Se and BF₃. In presence of BF₃, SeCF₂ polymerizes even at ?80°C. Above 150°C (F₂CSe)n depolymerizes to F₂C = Se and Halogen addition to F₂C=Se produces F₂XCSeX (X = Cl, Br). The compound Cl₂FCSeCl could be synthesized by the reaction of CSe₂ with ClF and Cl₂. These selenenylchlorides react with tin producing the corresponding symmetric diselenides whereas with AgCN the selenocyanates are formed. can be transformed to through halogen exchange reaction with BX₃ (X = Cl, Br). XC(S)Cl reacts with Hg(SeCF₃)₂ to give CF₃SeC(S)X (X = F, Cl. CF₃Se), from which the corresponding sulfenylchlorides can be synthesized by chlorine addition. I.r., n.m.r., and mass spectra of the newly prepared compounds are reported.     

Gaussian Amplitude Amplification for Quantum Pathfinding

We study an oracle operation, along with its circuit design, which combined with the Grover diffusion operator boosts the probability of finding the minimum or maximum solutions on a weighted directed graph. We focus on the geometry of sequentially connected bipartite graphs, which naturally gives rise to solution spaces describable by Gaussian distributions. We then demonstrate how an oracle that encodes these distributions can be used to solve for the optimal path via amplitude amplification. And finally, we explore the degree to which this algorithm is capable of solving cases that are generated using randomized weights, as well as a theoretical application for solving the Traveling Salesman problem.     

The Conformation of Sterically Congested Seven-Membered Rings Containing Tetracoordinate Germanium(IV): A First X-Ray Crystallographic Structure Determination

The X-ray crystallographic analysis of 6,6-dimethyl-2,4,8,10-tetra-tert-octyl-dibenzo[d,f][1,3,2]dioxagermepin, 1 is reported. In the solid-state conformation of 1, the dihedral angle about the C─C sp²-sp ² σ bond connecting the two aryl rings is 50.1°. The observed C₂ symmetry in the solid-state conformation of 1 is consistent with the previously suggested solution conformation.     

Molecular flow and wall collision age distributions

The use of storage cells has become a standard technique for internal gas targets in conjunction with high energy storage rings. In case of spin-polarized hydrogen and deuterium gas targets the interaction of the injected atoms with the walls of the storage cell can lead to depolarization and recombination. Thus the number of wall collisions of the atoms in the target gas is important for modeling the processes of spin relaxation and recombination. It is shown in this article that the diffusion process of rarefied gases in long tubes or storage cells can be described with the help of the one-dimensional diffusion equation. Mathematical methods are presented that allow one to calculate collision age distributions (CAD) and their moments analytically. These methods provide a better understanding of the different aspects of diffusion than Monte Carlo calculations. Additionally it is shown that measurements of the atomic density or polarization of a gas sample taken from the center of the tube allow one to determine the possible range of the corresponding density weighted average values along the tube. The calculations are applied to the storage cell geometry of the HERMES internal polarized hydrogen and deuterium gas target. Received 9 July 2001 and Received in final form 18 September 2001