Band structure of even and ions of odd polyenes

The analysis of experimental data for singlet transitions (E _n) of even polyenes (I), cations (II) and anions (III) of odd polyenes show that for infinite chains E (I)/E (II)=E (I)/E (III) = 2:1. It is shown that the energy gap is equal for the three systems. In cases (II) and (III) there is a level (NBMO) in the gap which is vacant in (II) and occupied in (III). That is why the first optical transition in (II) and (III) depends on the semiwidth of the gap.     

Wedderburnzerlegung für Jordan-Paare

In the first section we summarize some properties of Jordan pairs. Then we state some results about some groups defined by Jordan pairs.In the next section we construct a Lie algebra to a Jordan pair. This construction is a generalization of the wellknown Koecher-Tits-construction. We calculate the radical of this Lie algebra in terms of the given Jordan pair.In the last section we prove a Wedderburn decomposition theorem for Jordan pairs in the characteristic zero case. Some special cases in arbitrary characteristic have been shown by R. Carlson (see [5]). Also we show that any two such decompositions are conjugate under a certain group of automorphism. Analogous theorems will be shown for Jordan Triples.     

Lotketten in Speziellen Hjelmslev-Gruppen

Let be given a geometric structure with a set of lines and a symmetric orthogonality relation. F. Bachmann defined in [3] chains of perpendiculars in such a structure, and studied those chains in Hjelmslev-groups. All AGS-groups (= groups treated in [1]) are Hjelmslev-groups, and the theory of Hjelmslev-groups includes also Hjelmslev's concept of Allgemeine Kongruenzlehre. In Hjelmslev-groups, chains of perpendiculars are closely related to the group generated by the points. We establish some results about chains of perpendiculars in special classes of Hjelmslev-groups.     

Über geschlossene Regelflächen im elliptischen Raum

On a ruled closed surface in the elliptic 3-space two integral invariants are considered: the aperture distance of a curve orthogonal to the generating lines of , and the aperture angle of an orthogonally circumscribed tangent surfaces. By means of these integral invariants and by considering certain ruled surfaces associated to one finds the geometric meaning of further integral invariants. If is generated by the binormals of a curve one obtains some properties of closed curves in the elliptic 3-space.     

SIMS and flash desorption studies of nickel oxygen interaction

O₂ exposure of polycrystalline nickel at 300 K results in characteristics changes of secondary ion emission. These can be described by a model which is in good agreement with corresponding LEED, AES, XPS, and ΔΦ results of other authors. According to this model, oxygen can be bonded on Ni in at least five different phases:

1. chemisorption, indicated by a rapid increase of Ni⁺, Ni ₂ ⁺ , and Ni₂O⁺ (≦5 L);
2. a rearranged chemisorption layer, characterized by a drastic decrease of Ni⁺, Ni ₂ ⁺ , and Ni₂O⁺ (5–15 L);
3. nickel oxide (NiO) responsible for a strong NiO^?- and NiO ₂ ^? -emission (≦40 L);
4. oxygen on top of this NiO layer, producing a final increase of Ni⁺ and NiO⁺ and a O₂-flash signal at 400 K (>40 L);
5. bulk dissolved oxygen in thermal equilibrium with a chemisorption layer (after several exposure/heating cycles).

During ion bombardment of a 100 L O₂ exposed Ni surface these different binding states occur in a reversed order of succession. O₂-flash signals at 400 and 1100 K, related to drastic changes in secondary ion emission at 400, 700, and 1100 K, reflect the disappearance of various oxygen binding states. The exchange between different oxygen phases was studied by¹⁶O₂/¹⁸O₂ isotope experiments.     

Density fluctuations from elastic dipoles in glasses at low temperatures

The contribution of the population fluctuations of two-level systems in glasses to the dynamic structure factor is calculated using the concept of elastic dipoles. Describing the two-level systems by the tunneling model, with reasonable assumptions about the distribution of tunneling frequencies an essentially logarithmic decay in time of is obtained.     

Hyperfine structure of six low-lying fine structure levels of191Ir and193Ir and the191Δ s 193 hyperfine anomaly

The hyperfine interaction constantsA andB of six low-lying metastable fine structure states of the two iridium isotopes¹⁹¹Ir and¹⁹³Ir and the electronicg-factors of these levels have been measured using the atomic-beam magnetic-resonance method. From the values of the magnetic-dipole interaction constantsA, corrected for off-diagonal perturbations, we extracted the hyperfine anomaly of a pure 6s-electron state:¹⁹¹ Δ _s ¹⁹³ =0.64(7)%. Using nonrelativistic approximations for the effective radial parameters the nuclear electric-quadrupole moments were obtained:Q(¹⁹¹Ir) = 0.81(21)b,Q(¹⁹³Ir)=0.73(19)b     

Gamma spectroscopic study of105Ru

Theγ radiation following thermal neutron capture in¹⁰⁴Ru has been investigated through singles, coincidence, and angular correlation measurements in order to solve existing discrepancies and to complete the knowledge about the transitional odd-N nucleus ₄₄ ¹⁰⁵ Ru₆₁. The resulting level andγ-decay scheme is found to be very similar to that of the odd-Z transitional nucleus ₆₁ ¹⁴⁹ Pm₈₈. Between the 11/2^?, 15/2^?, and 19/2^? states which are interpreted as members of the decoupled band, built on the unique parity 11/2^? single particle state, low spin states of negative parity are found at surprisingly low excitation energies above the 11/2^? state. In the frame of the particleplus-rotor model their positions would require a sharp decrease of the rotational parameter with increasing collective angular momentum of the soft core.     

Pion photoproduction on197Au to ground and isomeric states in197Hg

The lifetime of the 331.3 keV 0 ₂ ⁺ state in¹⁰⁰Zr has been measured at the gas-filled recoil separator for fission products JOSEF. By observing the delayed coincidences between theβ-particles populating the level and theE0 conversion electrons from its decay into the ground state, a half-life of 3.37±0.30 ns has been obtained. From the measured lifetime and the relative intensities of the 0 ₂ ⁺ →0 ₁ ⁺ and 0 ₂ ⁺ →2 ₁ ⁺ transitions, values of 0.493±0.015 for theE0 strength parameterρ, and of 16 single particle units forB(E2,2 ₁ ⁺ → 0 ₂ ⁺ ) have been deduced. The enhanced nature of theE0 transitions suggests mixing of the 0 ₁ ⁺ and 0 ₂ ⁺ states which may be estimated by comparing the experimentalB(E2) values for the 2 ₁ ⁺ →0 ₁ ⁺ and 2 ₁ ⁺ →0 ₂ ⁺ transitions with the predictions of the asymmetric VMI model.