52 research outputs found
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
Effect of technological and constructive parameters on the integrity of the bottom of aluminum reduction cells during flame preheating
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
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