Contrast mechanisms in photothermal scanning tunneling microscopy

By irradiation of the tunneling junction of a scanning tunneling microscope with intensity-modulated laser light a gap-width modulation due to thermal expansion of tip and sample was produced. Photothermal images were obtained by spatial mapping of the resulting modulation of the tunneling current or its logarithm. The various mechanisms responsible for the observed contrast are discussed quantitatively. In case of a highly corrugated gold film on mica the contrast arises mainly from either the current variations caused by the non-zero reaction time of the current control loop or from a geometry factor. In both cases the images reflect certain properties of the sample topography. On the other hand, for a liquid-crystal film adsorbed on graphite a contrast on a molecular scale was found which is attributed to variations of the effective barrier height.     

On the asymptotic behaviour of Spitzer's model for evolution of one-dimensional point systems

A nearest-neighbor gradient dynamics of one-dimensional infinite particle systems is considered; the model admits a two-parameter family of stationary configurations. Some domains of attraction of stationary configurations are described, and the continuum (hydrodynamical) limit of the system is investigated. It is shown that the mean density of points satisfies a nonlinear diffusion equation in the hydrodynamical limit.Research supported by I.H.E.S., Bures-sur-Yvette, France.     

Übergangsmetallketen-verbindungen: XXIII. Röntgenstrukturanalyse von α-[Dicarbonyl(η5-cyclopentadienyl)trimethylphosphinwolframa]α-(4-methylphenyl)essigsäuremethylester

Transition-metal-substituted η¹-ketenes react with methanol to form methyl acetate with the metal in the α-position. X-Ray analysis proves the trans-position of the two carbonyl ligands.     

Electrochemical deposition of copper phosphides

Summary Methods for preparation of copper phosphides at ambient temperatures by electrodeposition are presented. From P₄/PCl₃/Acetonitrile/TBA-BF₄/Cu⁺ (solvated) Cu₃P and Cu₃P₂ can be obtained at different deposition potentials.

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Elektrochemische Abscheidung von Kupferphosphiden

Zusammenfassung Es werden Verfahren zur Herstellung von Kupferphosphiden bei ambienten Temperaturen beschrieben. Aus der Anordnung P₄/PCl₃/Acetonitril/TBA-BF₄/Cu⁺ (solvatisiert) können Cu₃P und Cu₃P₂ bei verschiedenen Abscheidungspotentialen erhalten werden.