Size Quantization in Layered HgI2 Colloids

M. W. Peterson, O. I. Micic, A. J. Nozik

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Colloidal particles of HgI2 with a particle size less than about 25 Å are formed by the reaction of HgCl2 with NaI in acetonitrile. The particles are charged with Cl- ions that fill normally empty tetrahedral coordination sites at the edges; therefore they have an empirical formula HgI2Cl0.60-6. About 40% of the mercury in the colloidal solution is in the form of the ionic complex HgI2Cl-. These conclusions are based on extensive spectroscopic studies of various Hg-I-Cl species and experiments involving ultracentrifugation, ultrafiltration, and treatment of the colloids with ion-exchange resins. The absorption spectrum of the colloidal HgI2 consists of three peaks at 4.26, 4.94, and 6.04 eV, and is attributed to size quantization effects. This spectrum is consistent with the first three allowed transitions in a simple particle-in-a-box model with infinite potential barriers in which the colloidal particles have the usual tetrahedral, layered structure of red HgI2, with dimensíons of 26.1 Å perpendicular to the layer plane (four layers thick) and 13.3 Å in the direction parallel to the layer plane.

Original languageAmerican English
Pages (from-to)4160-4165
Number of pages6
JournalJournal of Physical Chemistry
Issue number14
StatePublished - 1988

NREL Publication Number

  • ACNR/JA-236-11375


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