Two-dimensional order in mercury-supported langmuir films of fatty diacids

Lilach Tamam, Benjamin M. Ocko, Moshe Deutsch

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The structure of mercury-supported Langmuir films of dicarboxylic acid molecules with 13 ≤ n ≤ 22 carbons is studied by X-ray methods and surface tensiometry. The molecules lie surface-parallel, forming mono-, bi-, or trilayers, depending on coverage. All films exhibit a full 2D order of the same single-molecule oblique unit cell. In particular, the distinct odd-even structure difference of 3D crystals of the same molecules is not observed. The unit cells width and angle show a small systematic decrease with n, while the length increases commensurately with the molecular length. These results show the films to consist of closely packed, extended, polymer-like chains of diacid molecules, bound by their carboxyl end groups. Evidence is presented for the inclusion of a single mercury atom in the carboxyl-carboxyl bond. The possible conformation of this bond and implications of the parity-independent structure are discussed.

Original languageEnglish
Pages (from-to)15586-15597
Number of pages12
Issue number44
StatePublished - 6 Nov 2012

Bibliographical note

doi: 10.1021/la3034325


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