FTIR-spectroscopy as a highly sensitive technique to study adsorption and desorption on ionic film and single crystal surfaces

Sample/spectrum relationships are investigated using both a low resolution rapid-scanning NIR monochromator and a Fourier transform instrument capable of high resolution and are evaluated in terms of whether or not the resolution of the instrument is sufficient for measuring the natural bandwidths corresponding to the sample. Based on the sample/spectrum relationship a criterion is developed which must be followed in order to apply either derivative spectroscopy or deconvolution to enhance the resolution of overlapped bands without generating spectral artifacts.     

Preparation of β-hydroxyesters from isoxazolines. A selective Nibpy-catalyzed electrochemical method

An electrocatalytic method for the reductive N-O cleavage of isoxazolines is described. Ni⁰bpy, generated in situ, was used to promote selective ring opening of 3-methoxy-5-phenylisoxazoline (1a) and 3-methoxy-[4,5]cyclohexylisoxazoline (1b). DMF and NaI were used as solvent and supporting electrolyte, and β-hydroxyesters 2a and 2b were obtained in high yields respectively, after acid hydrolysis. β-Hydroxynitriles 3a and 3b were also identified as side products.     

Characterization of iron-silicon thin films by means of electron diffraction and X-ray spectroscopy

Iron-silicon thin films have been characterized by means of analytical transmission electron microscopic methods. Under certain conditions — composition and annealing temperature — these films exhibit thermoelectric behavior. In particular, the morphology and phase formation which results from annealing of these films, and doping with oxygen and nitrogen, are of interest. The thermoelectric phase -FeSi₂ is formed at temperatures above 500°C. This phase is transformed into electrically conducting phases at about 1000°C. A small oxygen content does not influence this crystallization process. If the oxygen content is higher than 15 atom-% the electrically conducting phases exist even at 500°C. The presence of a small nitrogen content inhibits the formation of the -FeSi₂ phase. The development of silicon and iron nitrides is possible.     

Polymer melt flow measurements by laser doppler velocimetry

Laser Doppler velocimetry (LDV) is a new tool for fluid dynamics studies. Using LDV the velocity vector field can be measured without disturbing the flow itself. However, in polymer melt fluid dynamics difficulties arise because of temperature problems, the relatively high pressure involved, and the often extremely slow flows. In this paper a LDV system is described which was set up especially for polymer melt flow investigations.     

Impedance laser spectroscopy in a small RF-excited neon discharge

Laser impedance spectroscopy in a miniature neon RF-discharge operating at 0.27 bar was performed. The dominant role of the metastable atoms to the size and the sign of the RF-signal was investigated. Excellent linearity of the RF-signal but poor detection sensitivity of excited metastable neon atoms were found at low laser powers.     

Tetragonal low-temperature structure of LiAl

The cubic face-centered structure of LiAl (, at ) transforms into a tetragonal body-centered structure (I4₁/amd, , at ). This first-order phase transition at about during heating is probably the reason for the so-called “ anomalies” in some physical properties like specific heat, electrical resistivity and nuclear-spin lattice relaxation. This transition seems to be correlated with the composition Li:Al of the alloy and the amount of Li vacancies.     

Binucleare Nickel(0)-Komplexe mit „Schlangenliganden”︁ vom 1-Azadientyp: Modellsysteme der oxidativen Kopplung von 1-Azadienen und 1,3-Dienen am Nickel(0)

Binuclear Nickel(0) Complexes with “Snake Ligands” of 1-Azadiene Type: Model Systems of the Oxidative Coupling of 1-Azadienes and 1.3-Dienes at Nickel(0) Synthesis, properties, and reactions of dimeric nickel(0) complexes with special 1-azadiene typ ligands (“snake ligands”) are described. The X-ray analysis of a typical compound (Bis-(bis-cinnamaldehyde-N,N'-propylendiimine)-dinickel(0)) shows that both central atoms have the coordination number 3. The four 1-azadiene groups are coordinated in a different way: unidendate coordination by N-Ni(1) bond and bidendate coordination by N-Ni(1) and olefine-Ni(2) bond. The compound is a good model system for the oxidative coupling reaction of 1-azadienes with 1.3-dienes at 2 nickel(0) centres. IR and electronic spectra show other complexes with this type of ligands to have an analogous coordination sphere.     

Beiträge zur Chemie der Silicium—Stickstoff-Verbindungen, 21. Mitt.

Zusammenfassung Durch Umsetzung von Disilbercyanamid mit Organyl- und Alkoxy-halogensilanen wurden 9 bisher unbekannte zweifach silylsubstituierte Carbodiimide der Stoffgruppen (R₃SiN)₂C, [(RO)₃SiN]₂C, (R₂RSiN)₂C und R₃SiNCNSiR₃ dargestellt und in ihrer Struktur über¹⁴N- und¹H-kernmagnetische Resonanzmessungen, IR- und Raman-Spektren eindeutig als Carbodiimidderivate aufgeklärt.20. Mitt.:U. Wannagat undH. Kuckertz, Angew. Chem.75, 95 (1963).Zugleich 2. Mitt. über silylsubstituierte Carbodiimide; 1. Mitt.J. Pump undU. Wannagat, Ann. Chem.652, 21 (1962); Angew. Chem.74, 117 (1962); Österr. Chemiker-Ztg.62, 319 (1961).     

Smooth projective translation planes

A projective plane is called smooth if both the point space and the line space are smooth manifolds such that the geometric operations are smooth. We prove that every smooth projective translation plane is isomorphic to one of the classical planes over , , or .Dedicated to Professor Dr. H. Salzmann on the occasion of his 65th birthday