Abstract
The rigid-rod surfactants [n]staffane-3-car boxy lates (1[n]) readily form Langmuir-Blodgett films when = 4 and, with some effort, also when = 3. The area per molecule, extrapolated to zero pressure, is nearly independent of the counterion (26.0 Å2/molecule). Bilayer thickness in a multilayer assembly is 25.8 ± 0.1 Å for Ca2+ 1 [3], 32.2 ± 0.1Å for Ca2+ 1[4],and 31.4 ± 0.1 Å for Cd2+ as determined by low-angle X-ray reflection. Ellipsometry yields the values 27.2 ± 1.0,33.2 ± 1.0, and 32.6 ± 1.0 Å, respectively. The average tilt angle deduced from the difference between 1[3] and 1[4] is 17 ± 5°. Independent IR measurements at normal incidence on Ge and grazing angle incidence on Au substrate yield the values 28 ± 2° and 19 ± 2°, respectively. Only IR measurements were possible for a monolayer. They yielded the value 27 ± 2° at normal incidence on Ge and a distinctly different result at grazing incidence on Au, 0–10°. The larger average tilt values on the Ge surface are attributed to surface roughness.
Original language | English |
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Pages (from-to) | 2740-2746 |
Number of pages | 7 |
Journal | Langmuir |
Volume | 8 |
Issue number | 11 |
DOIs | |
State | Published - 1 Nov 1992 |