Abstract
By first-principles methods we analyze the optical response of transparent dense sodium as a function of applied pressure. We discover an unusual kind of charge-transfer exciton that proceeds from the interstitial distribution of valence electrons. The absorption spectrum is strongly anisotropic, which, just at pressures above the metal-insulator transition, manifests as sodium being optically transparent in one direction but reflective in the other. This result provides key information about the crystal structure of transparent sodium, a new unconventional inorganic electride.
- Received 25 February 2010
DOI:https://doi.org/10.1103/PhysRevLett.104.216404
©2010 American Physical Society
Synopsis
Pressure dulls shiny metals
Published 28 May 2010
At high pressure, the simple metal sodium shows complex behavior, including directional transparency.
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