Proton tunnelling in asymmetric complexes

The effect of proton tunnelling on the internal vibrations of the complexed moieties in hydrogen bonded systems of general formula A¹HA² is considered, for both the cases of a symmetric and asymmetric double minimum potential.In favourable situations, the form of the proton potential can be inferred from the appearance of the internal modes in the infrared spectrum, and checked in the deuterium bridged analogue. The method is applied to the (4 MePyHPy)⁺ cation, and indicates a single minimum in the proton potential.     

A note on solving Volterra integral equations with convolution kernels

A method described previously by the authors is applied to certain smooth kernels of convolution type in order to obtain numerical solutions to certain Volterra integral equations. Several one-dimensional approximation techniques are compared, and the finite Tchebycheff expansion is found to be most effective in terms of decreased computational effort. A number of numerical examples are cited.     

The thermal activation energy of crystalline Sb2Se3

Crystalline Sb₂Se₃ exhibits intrinsic-like electrical conductivity behavior with varying thermal activation energies. An explanation is offered based on the incorporation of native defects during crystal growth.     

Increasing the magnetic helicity content of a plasma by pulsing a magnetized source

By operating a magnetized coaxial gun in a pulsed mode it is possible to produce large voltage pulses of duration approximately 500 mus while reaching a few kV, giving a discrete input of helicity into a spheromak. In the sustained spheromak physics experiment (SSPX), it is observed that pulsing serves to nearly double the stored magnetic energy and double the temperature. We discuss these results by comparison with 3D MHD simulations of the same phenomenon.     

Bounded degree acyclic decompositions of digraphs

An acyclic decomposition of a digraph is a partition of the edges into acyclic subgraphs. Trivially every digraph has an acyclic decomposition into two subgraphs. It is proved that for every integer s2 every digraph has an acyclic decomposition into s subgraphs such that in each subgraph the outdegree of each vertex v is at most . For all digraphs this degree bound is optimal.     

Tunable laser-sideband generation in InSb

The resonant third order non-linear susceptability in InSb has been employed to generate a magnetically tunable cw laser sideband near 5 μm.     

An optically pumped waveguide laser with mesh reflectors

An optically pumped far infrared waveguide laser has been operated using metallic meshes as laser reflectors. The radiation modes sustained in the waveguide laser have been examined, and the use of the laser for magneto-optical measurements demonstrated.