Positional order in Langmuir monolayers: An X-ray diffraction study

V.M. Kaganer, G. Brezesinski, H. Möhwald, P.B. Howes, K. Kjær

    Research output: Contribution to journalJournal articleResearch


    The structural phase transition from the hexagonal to a distorted-hexagonal (centered rectangular) phase (the LS-S transition) in Langmuir monolayers of octadecanol is studied in a grazing incidence x-ray diffraction experiment. We find algebraic decay of positional correlations, which suggests solid-like order in both phases at the distances accessible in the present x-ray diffraction experiment. The transition is accompanied by strong positional disorder, which is evident from the drastic increase of the exponent eta to values eta>2 close to the transition. Remarkably, on approaching the transition, the continuous increase of eta is apparent already at 20 degrees C above it. The positional disorder is attributed to elastic distortions around pretransitional fluctuations. [S1063-651X(99)10102-8].
    Original languageEnglish
    JournalPhysical Review E
    Issue number2
    Pages (from-to)2141-2152
    Publication statusPublished - 1999


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