Arrangement of trace metal contaminations in thin films of liquid crystals studied by X-ray standing wave technique |
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| Affiliation: | 1. London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary''s Campus, Imperial College London, Norfolk Place, London W2 1PG, UK;2. Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary''s Campus, Imperial College London, Norfolk Place, London W2 1PG, UK;3. Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK;4. School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK;5. Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK;1. Department of Biology, Carleton University, Ottawa, Ontario K1S 5B6, Canada;2. Environment Canada, Science and Technology Branch, Raven Road, Carleton University, Ottawa, Ontario K1S 5 B6, Canada;3. Biology Department, Acadia University, 33 Westwood Avenue, Wolfville, Nova Scotia B4P 2R6, Canada |
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| Abstract: | X-ray standing wave method has been applied to investigate the molecular organization in Langmuir–Blodgett films of liquid-crystalline lanthanide complex deposited on silicon substrates. The X-ray standing waves measurements were carried out at BESSY II on the beamline KMC-2. Energy spectra of characteristic fluorescence emitted from the samples have been recorded at each point in the X-ray reflectivity curve as the incident angle was scanned through the total external reflection region. The integrated intensity under selected peaks was analyzed as a function of the incident angle. Incorporation of metal ions (Fe, Zn, Cu, Ca) to the Langmuir monolayer from the triply distilled water subphase has been established. Owing to the element selectivity of X-ray standing wave technique the arrangement of several types of metal ions inside the Langmuir–Blodgett films was studied individually. The experimental data revealed that the shape of the fluorescence curves for the contamination metal ions is distinctly different indicating considerable differences in the lateral distribution of these ions in the film. These results may be attributed to the phase separation in Langmuir monolayer of liquid-crystalline lanthanide complex due to the incorporation of metal ions from the water subphase. |
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