X-ray diffraction study of heneicosanol monolayers on the surface of water

M. C. Shih*, T. M. Bohanon, J. M. Mikrut, P. Zschack, P. Dutta

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


We have studied Langmuir monolayers of CH3(CH2) 20OH (heneicosanol) using x-ray diffraction. Over the temperature range 7-55°C, the monolayer isotherms show only one discontinuity, which may be either a "flat section" or a "kink;" we find that these are transitions between tilted and untilted phases. There are several untilted phases, with hexagonal and distorted-hexagonal structures, as in monolayers of the corresponding (heneicosanoic) acid. However, in contrast to the acid, when the pressure is lowered the molecules tilt only towards a next-nearest neighbor. The dependence of the lattice spacings on pressure and temperature indicate that the monolayer does not form a "tilted hexagonal" phase, even at temperatures where the untilted phase is hexagonal (rotator-II).

Original languageEnglish (US)
Pages (from-to)4485-4488
Number of pages4
JournalThe Journal of Chemical Physics
Issue number6
StatePublished - 1992

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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