Layers of Cold Dipolar Molecules in the Harmonic Approximation

We consider the N-body problem in a layered geometry containing cold polar molecules with dipole moments that are polarized perpendicular to the layers. A harmonic approximation is used to simplify the hamiltonian and bound state properties of the two-body inter-layer dipolar potential are used to adjust this effective interaction. To model the intra-layer repulsion of the polar molecules, we introduce a repulsive inter-molecule potential that can be parametrically varied. Single chains containing one molecule in each layer, as well as multi-chain structures in many layers are discussed and their energies and radii determined. We extract the normal modes of the various systems as measures of their volatility and eventually of instability, and compare our findings to the excitations in crystals. We find modes that can be classified as either chains vibrating in phase or as layers vibrating against each other. The former correspond to acoustic and the latter to optical phonons. Instabilities can occur for large intra-layer repulsion and produce diverging amplitudes of molecules in the outer layers. Lastly, we consider experimentally relevant regimes to observe the structures.Comment: 17 pages, 20 figures, accepted versio

Nanometals: Synthesis and Application in Energetic Systems

A survey of metal nanopowders or nanometals (mostly produced by electrical explosion of wires) usage in different energetic systems is carried out with the focus on nanometals combustion efficiency. Improved kinetic characteristics of chemically reacting systems (ignition, burning rate enhancement for propellants, explosives, and thermites) are typical for nanoaluminum, nAl. A weak correlation between nAl properties and the slow oxidation parameters was found as the result of a very wide scatter in powder characteristics. The burning rate enhancement was analyzed for nAl-loaded solid propellants. The most promising energetic systems are nAl-loaded solid fuels (HTPB-based, ice-based, etc.) with chemically inert matrices