Vibrational resonances below 5 MeV in the fission of 240Pu

Using the ²³⁹Pu(d, pf) reaction, the next lower K^π = 0⁺ vibrational resonance below 5 MeV in the deformed potential of ²⁴⁰Pu was located at 4.55 MeV. The resultant spacing of fission vibrations near 5 MeV in the second minimum is 500 keV. A resonance at 4.70 MeV is interpreted as the K^π = 0^? vibration coupled to the 4.55 MeV K^π = 0⁺ state, which yields E(K^π = 0^?) = 150 keV relative to the ground state of the second minimum.     

Rotational diffusion of dyes in solvents of low viscosity from transient-dichroism experiments

Rotational diffusion data from pulsed laser experiments are presented for dye molecules dissolved in alcohols and non-alcohols. Cresyl violet and fluorescein both exhibit strong dependence of the rotational motion upon solvent molecular structure. In complete contrast the rotational diffusion of the oblong dyes pyronine G and acridine orange do not reveal any specific solute-solvent interaction.     

Isobaric analogue resonances in proton scattering on Ba

Extensive experimental data for the resonance scatttering of protons to the ground state and first excited state in ¹³⁸Ba are presented. A Breit Wigner analysis with a background term of the form Σ_n(a_n/Eⁿ) is performed and the extracted background function is compared with optical-model calculations using the parameters given in a detailed investigation by Perey. Neutron spectroscopic factors calculated in different ways from this data are compared with the corresponding factors from (d, p). An accurate determination of resonance energies for the first two resonances reveals a deviation from a constant Coulomb shift of the order of 10 keV.     

Die Phlorglucide von Dryopteris viliarii (Bell.) Woynar und anderer Farne der Gattung Dryopteris sowie die mögliche Abstammung von D. filix-mas (L.) Schott

The phloroglucides of the ferns of the Dryopteris filix-mas complex; i.e. D. abbreviata, D. filix-mas s. str. and D. borreri (diploid and triploid) as well as those of D. villarii, subspvillarii and subsp. pallida were reinvestigated with improved semiquantitative analytical methods. The phloroglucides of D. aitoniana and D. athamantica were examined for the first time. The results (table 1) are compatible with the hypothesis, without proving it, that the allotetraploid species D. filix-mas s. str. originated from a hybrid of D. abbreviata with D. villard (with subsequent doubling of its chromosomes) and the apogamous triploid D. remota from D. assimils with diploid D. borreri, and the equally apogamous triploid D. borreri from a hybrid of D. abbreviata (or a related diploid sexual taxon) with diploid D. borreri. D. aitoniana contains a large amount of trisflavaspidic acid but no filixic acid and differs in this respect from the three representatives of the D. filix-mas complex.     

Zur Tilgung geradliniger Schwingungen mit Hilfe des Zentrifugalpendels

Ohne Zusammenfassung     

On the interaction of cesium with cleaved GaAs(110) and Ge(111) surfaces: Work function measurements and adsorption site model

The work function of UHV cleaved p-Ge(111) and n-GaAs(110) surfaces has been measured in dependence of the Cs coverage. At very low coverages θ < 0.001 the decrease of the contact potential difference is extremely steep. For GaAs the initial slope of the CPD versus coverage curve amounts to ?740 eV for Ge to ?130 eV per monolayer. Up to the saturation coverage the curves exhibit straight line segments with breaks at distinct coverages. Breaks are found for GaAs at approximately $\text{1}\text{12}$, $\text{1}\text{6}$, and $\text{1}\text{3}$ of a monolayer, for Ge at about $\text{1}\text{12}$, $\text{1}\text{4}$, $\text{1}\text{2}$, and $\text{3}\text{4}$. A new model is developed to explain this behaviour. It is based on the assumption of specific adsorption sites for the Cs atoms at the surfaces. With this model the experimental results, including the breaks, may be described in the whole coverage range from θ = 0.03 up to the saturation. Furthermore the dipole moments derived from the straight line segments are in excellent agreement with those values calculated for different surface molecules between the adsorbed cesium and substrate atoms at the specific adsorption sites.