title: Molecular rearrangement in a zinc stearate Langmuir film dependent on a film preparation method studied using polarization-modulation infrared reflection absorption spectroscopy and X-ray absorption fine structure.
abstract: Molecular dynamic rearrangement in a Langmuir (L) film of zinc stearate in a cross section image has been analyzed by employing polarization modulation infrared reflection spectrometry (PM-IRRAS) and X-ray absorption fine structure (XAFS). The number of coordination on a zinc cation is evaluated by XAFS, and the coordination structure of the carboxylic group is revealed by the IR analysis. An L film prepared at a fixed area without using film-compression bar exhibits time-dependent change of the coordination structure about a zinc cation, and it attains a highly ordered coordination structure in the carboxylic group region. However, an L film prepared by the Langmuir technique using a compression bar exhibited ignorable spectral changes in both IR and X-ray analyses. The hydrocarbon chains in the compressed L film are better uniformed than the uncompressed film, but the uniformed molecular arrangement of the carboxylic group is restricted to be rearranged, and it does not attain a stable structure in terms of coordination on the zinc cation.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Tokyo 152-8551, Japan.
authors.forename: Maiko
authors.initials: M
authors.lastname: Muro
authors.forename: Makoto
authors.initials: M
authors.lastname: Harada
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Okada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hasegawa