Quantitative energy level correlations for linear,bent and internally rotating triatomic molecules

This paper is concerned with the study of the quantitative correlation of the rotation-bending energy levels of a linear or bent triatomic molecule with the energy levels of the molecule when there is free internal rotation of a diatomic fragment [as in, for example, Ar(HCl)]. The LiNC and KCN molecules are used as model systems. A correlation parameter γ_r is introduced to quantify the position a molecule occupies in these correlation diagrams; this parameter has the value +1 for an ideal bent molecule, ?1 for an ideal linear molecule, and ?3 for an ideal free internal rotor triatomic molecule. The rotation-bending energy levels of the HCN-HNC isomerization system, and of the double minimum HO₂ system, are also studied.     

Supercurrents

Supercurrents that provide irreducible off-shell representation of N-extended supersymmetry with maximum $\text{spin}\text{?}\text{1}\text{2}\text{N}$ are constructed as bilinears of massless on-shell superfields. The corresponding prepotentials are derived and used to construct maximally gauge-invariant field theories with maximum $\text{spin}\text{?}\text{1}\text{2}\text{N}$. The construction of non-conformal theories using these irreducible field multiplets is discussed; in particular the superfield form of massive spin 1 is given for N = 2 and compensating fields are proposed for N = 4 Poincarésupergravity. We also show how the components of supercurrents may be simply obtained with the aid of the “tableaux calculus” and we work out in detail several N = 4 and N = 8 examples.     

The superoxide ion on supported tungsten: Evidence for surface mobility

The EPR spectrum of oxygen adsorbed on silica supported tungsten prepared from W(CO)₆ has been assigned to O^?₂ on the basis of the g tensor and the hyperfine structure observed with ¹⁷O enriched oxygen . A temperature dependent signal shape above 77 K indicates anisotropic motion of O^?₂ on the surface.     

Constraints on nucleon decay via invisible modes from the Sudbury Neutrino Observatory

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to "invisible" modes, such as n-->3nu. The analysis was based on a search for gamma rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16O. A limit of tau(inv)>2 x 10(29) yr is obtained at 90% confidence for either neutron- or proton-decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton-decay modes and 400 times more stringent than similar neutron modes.     

Do columnar defects produce bulk pinning?

From magneto-optical imaging performed on heavy-ion-irradiated YBa(2)Cu(3)O(7-delta) single crystals, it is found that at fields and temperatures where strong single vortex pinning by individual irradiation-induced amorphous columnar defects is to be expected, vortex motion is limited by the nucleation of vortex kinks at the specimen surface. In the material bulk, vortex motion occurs through (easy) kink sliding. Depinning in the bulk determines the screening current only at fields comparable to or larger than the matching field, at which the majority of vortices is not trapped by an ion track.     

On the Rayleigh conductivity of a bias-flow aperture

An analysis is made of the attenuation of sound by vorticity production in a bias flow aperture. A modified form of the Cummings equation describing unsteady flow through a small aperture is used to extend the linear theory of the bias flow conductivity of a circular aperture in a thin wall of Howe (1979. On the theory of unsteady high Reynolds number flow through a circular aperture. Proceedings of the Royal Society of London A 366, 205–233) to a wall of arbitrary thickness and to examine the influence acoustic nonlinearity within the aperture. Numerical results are compared with existing analytic predictions of linear theory. It is shown that attenuations predicted by both linear and nonlinear theories agree over a wide range of incident acoustic pressures, approaching in amplitude that required to maintain the steady mean flow through the aperture. The dominant nonlinear effect is a small reduction (less than about 5%) in the mean bias flow velocity. Application of the Cummings equation in the linear regime leads to a new, simple formula for the bias flow conductivity for a screen of finite thickness.