Direct observation of a surface charge density wave
Article Abstract:
Electron-phonon coupling produces a charge density wave (CDW) at the surface of a lead/germanium (111) crystal. The CDW is reversible, induced by temperature and its stability depends on electron-electron interactions. Periodic redistribution of valence charge, metal-nonmetal transition and lattice displacement occur during CDW formation. The reversible transition to the CDW state occurs at an onset temperature lower than that for structural transitions. With enhanced lattice distortion due to electron-electron interaction, the stability of the low-temperature phase increases.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Observation of negative electron-binding energy in a molecule
Article Abstract:
Dynamic stability plays a significant role in multiply charged molecular anions, and the superpositon of long-range Coulomb repulsion and short-range electron binding leads to a repulsive Coulomb barrier (RCB), trapping excess electrons. Photodetachment experiments have shown that the RCB can trap electrons in molecular orbitals distinguished by a negative binding energy. When sulphonate groups are added to cyclic copper phthalocyanine the energy of the corresponding molecular orbitals increases, resulting in the highest occupied molecular orbital of the tetra-anion.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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What is a wave?
Article Abstract:
It is difficult to find a definition for a wave. There is a fine line between non-wave-like and wave-like behavior. Waves are chemical, biological and physical phenomena and the core of matter and time. Bearing in mind various examples of waves, the best definition of wave is an organized propagating imbalance.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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