Electrostatic properties of adsorbed polar molecules: Opposite behavior of a single molecule and a molecular monolayer

Dudi Deutsch, Amir Natan, Yoram Shapira, Leeor Kronik

Research output: Contribution to journalArticlepeer-review

Abstract

We compare the electrostatic behavior of a single polar molecule adsorbed on a solid substrate with that of an adsorbed polar monolayer. This is accomplished by comparing first principles calculations obtained within a cluster model and a periodic slab model, using benzene derivatives on the Si(111) surface as a representative test case. We find that the two models offer diametrically opposite descriptions of the surface electrostatic phenomena. Slab electrostatics is dominated by dipole reduction due to intermolecular dipole-dipole interactions that partially depolarize the molecules, with charge migration to the substrate playing a negligible role due to electric field suppression outside the monolayer. Conversely, cluster electrostatics is dominated by dipole enhancement due to charge migration to/from the substrate, with only a small polarization of the molecule. This establishes the important role played by long-range interactions, in addition to local chemical properties, in tailoring surface chemistry via polar molecule adsorption.

Original languageEnglish
Pages (from-to)2989-2997
Number of pages9
JournalJournal of the American Chemical Society
Volume129
Issue number10
DOIs
StatePublished - 14 Mar 2007

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