Adsorption of H2 and CO on clean and oxidized (110) Pt

Binding states and sticking coefficients of CO and H₂ on clean and oxide covered (110) planes of Pt are examined using flash desorption mass spectrometry to characterize binding states and Auger electron spectroscopy (AES) to characterize oxide densities. It is found that on the oxide both adsorbates have new binding states with significantly higher binding energies than on the clean surface. For H₂ the binding states associated with the clean surface are also shifted to higher energies as the oxide coverage increases. The oxide state for H₂ desorbs with first order kinetics, and isotope exchange experiments are used to examine exchange between isotopes and between states. The initial sticking coefficients for CO are 1.0 and 0.85 on clean and oxidized surfaces, and the initial sticking coefficient for H₂ increases from 0.15 on the clean surface to 0.28 on the oxidized surface. Enhanced bonding on the oxide is interpreted in terms of models involving microfacets, electronic structure alteration, and compound formation.     

Evidence for an isomeric state in 216Th

A new α-line with E_α = 9.912±0.020 MeV is assigned to an isomeric state in ²¹⁶Th. It decays with a half-life of $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 180±40 μ}\text{s}$. There are indications for a dominating γ-branch.     

I. Allgemeine analytische Methoden, Apparate und Reagentien

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A new Mössbauer isotope for solid state investigations:174γb

The even-even isotopes of Yb are good probes for solid state investigations by Mössbauer spectroscopy. A disadvantage of the commonly used¹⁷⁰Yb is its low natural abundance of only 3%. We have developed a new source for Mössbauer spectroscopy with¹⁷⁴Yb which is superior to¹⁷⁰ Yb not only because of the higher isotopic abundance (32%) but also in resolution and f-factor.     

Die Bestimmung von ?thylendiamin in 2-Methylpiperazin

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Diophantine problems in variables restricted to the values 0 and 1

Let $\text{F}$x₁,…,x_s be a form of degree d with integer coefficients. How large must s be to ensure that the congruence $\text{F}$(x₁,…,x_s) ≡ 0 (mod m) has a nontrivial solution in integers 0 or 1? More generally, if $\text{F}$ has coefficients in a finite additive group G, how large must s be in order that the equation $\text{F}$(x₁,…,x_s) = 0 has a solution of this type? We deal with these questions as well as related problems in the group of integers modulo 1 and in the group of reals.     

Mittelwerte über Gitter

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Zur Modulation des Wandstromes in der geschichteten positiven Säule der Neon-Glimmentladung

It is shown, that the wall current of the striated positive column in a neon low pressure glow discharge is modulated with the frequency of the moving striations. There is a phase shift between wall currents of electrons and ions (～π/2–3/4π), A mass-spectrometric analysis of the ion currents shows Ne⁺ and Ne₂⁺ ions, both currents are modulated. The modulation factor of the electron and ion current reaches values near 100% and 50%, repectively. The behaviour of the modulated wall currents may by explained by the potential oscillations in the Langmuir sheath near the wall.     

Ein verbessertes UV-spektrophotometrisches Verfahren zur Bestimmung von Fenthion

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