Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9594520 | Surface Science | 2005 | 11 Pages |
Abstract
New features are observed in photoluminescence spectra of MgO smokes produced in controlled conditions, an experiment inspired by previous measurements on cleaved MgO(1Â 0Â 0). Upon photoexcitation at 5.17-5.45Â eV, most luminescence spectra observed can be decomposed into two bands, peaking at 3.82-3.86Â eV (the highest energy ever recorded in such experiment) and 3.20Â eV, respectively. It is assumed that the 3.82-3.86Â eV band is related to the luminescence at four-coordinated (4C) defect-free edge sites and that the 3.20Â eV band arises from the excitation transfer from 4C edge sites towards less-coordinated 3C sites. A minor contribution to the 3.20Â eV band observed upon excitation with 4.6Â eV photons is assigned to a direct excitation of 3C sites. Within these assumptions, water chemisorption-desorption is suggested to produce less-coordinated sites (the 3.20Â eV band increases in intensity) at the expense of 4C sites (the 3.84Â eV band decreases). The huge sensitivity of the 3.84Â eV/3.20Â eV branching ratio to the formation of defects on 4C edges is suggested to explain the lack of consensus about the photoluminescence of MgO.
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Romain Hacquart, Jean-Marc Krafft, Guylène Costentin, Jacques Jupille,