Dipole-dipole interactions among CH3Cl molecules on Ru(001): Correlation between work function change and thermal desorption studies

T. Livneh*, Y. Lilach, M. Asscher

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Work function change measurements (ΔΦ) combined with temperature programmed desorption (TPD) were employed to study layer growth mechanism and the CH3Cl dipole-dipole interactions on Ru(001), over the temperature range of 97 K-230 K. The activation energy for desorption (Ea) and the molecular dipole moment (μ) both decrease from 55.9 kJ/mol and 2.44 D, at the zero coverage limit, to 38.6 kJ/mol and 1.27 D, at one monolayer. This coverage dependence originates from strong dipolar lateral repulsion among neighbor CH3Cl molecules. Using a model introduced by Maschhoff and Cowin (MC) [J. Chem. Phys. 101, 8138 (1994)], the isolated adsorbed molecule's dipole moment, μ0 (2.35 D) and polarizability α(8.1×10-24 cm3), were extracted from TPD data. These values agree very well with μ0 (2.12 D) and α(9.2×10-24 cm3) obtained from work function change measurements by employing the same MC model. The ability to simulate both TPD and work function change data over a wide coverage range within the framework of a single electrostatic model has been demonstrated. It enabled better understanding of fine details of surface dipolar interactions.

Original languageEnglish
Pages (from-to)11138-11146
Number of pages9
JournalJournal of Chemical Physics
Volume111
Issue number24
DOIs
StatePublished - 22 Dec 1999

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