Bulk terminated NaCl(111) on aluminum: A polar surface of an ionic crystal?

W. Hebenstreit1,*, M. Schmid1, J. Redinger2,4, R. Podloucky3,4, P. Varga1

1 Institut für Allgemeine Physik, Technische Universität Wien, A-1040 Wien, Austria
2 Institut für Technische Elektrochemie, Technische Universität Wien, A-1060 Wien, Austria
3 Institut für Physikalische Chemie, Universität Wien, A-1090 Wien, Austria
4 Center for Computational Materials Science, Technische Universität Wien, A-1060 Wien, Austria
* Present address: Department of Physics, Tulane University, New Orleans, LA 79118, U.S.A.

Phys. Rev. Lett. 85 (2000) 5376-5379

Atomically resolved scanning tunneling microscopy reveals the existence of triangular (111) bulk terminated NaCl islands. The islands can be grown by subsequent adsorption of Na and Cl2 on Al(111) and Al(100) or by conversion of stoichiometric NaCl(100) islands to NaCl(111) via additional Na adsorption. The NaCl(111) islands have Na-Cl-Na sandwich structure. Ab-initio calculations of the electronic structure of these islands show that each of the Na atoms carries half a positive elementary charge, leaving the islands neutral and explaining the existence of an otherwise unstable surface.

Corresponding author: M. Schmid (schmid< encoded email address >).

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