Ellipsometric studies of behenic acid at the air‐water interface

Abstract

The rich phase behaviour of monolayers of behenic acid (=docosanoic acid) has been analyzed by null ellipsometry in isothermic and isobaric measurements. By using structural data known from x‐ray measurements the anisotropy and refractive indices in the vicinity of the S‐CS phase transition have been calculated with a minimum of model assumptions. The calculated values are: nsx=1.47. ncsx=1.48. nsz=1.54. ncsz=1.55. and anisotropy γ=nx/nz ≈︁0.95. It is also shown that ellipsometry is a very sensitive and convenient method of detecting phase transitions. Its value for quantifying the roughness of the monolayer in the close vicinity of phase transitions due to thickness and density fluctuations is shown by the measurement of the parabolic intensity variations of the ellipsometric angle δΔ. The intensity minimum at the phase transition is much wider than in the adjacent homogeneous phases.

Ellipsometry and X-ray Reflectivity Studies on Monolayers of Phosphatidylethanolamine and Phosphatidylcholine in Contact with n-Dodecane, n-Hexadecane, and Bicyclohexyl

“…Null Ellipsometer. The experimental set-up is described in detail elsewhere . The conventional PCSA null ellipsometer , is mounted on a custom rigid frame structure.…”

“…The experimental set-up is described in detail elsewhere. 21 The conventional PCSA null ellipsometer 22,23 is mounted on a custom rigid frame structure. A 4 mW HeNe laser is used as light source with a beam diameter of 0.8 mm.…”

Surface viscoelastic properties of floating polyelectrolyte multilayers films: A capillary wave study

“…The thicknesses of the multilayered films was measured using a Null ellipsometer [25], with an incident monochromatic He-Ne laser beam (λ = 632 nm). We measured the changes of the ellipsometric parameters Ψ and ∆, which describe the reflection of the incident beam close to the Brewster angle (θ = 50 • ) at the air-water interface.…”

Polyelectrolytes I: Polyanion/Polycation Multilayers at the Air/Monolayer/Water Interface as Elements for Quantitative Polymer Adsorption Studies and Preparation of Hetero-superlattices on Solid Surfaces

“…Floating polyelectrolyte complexed monolayers and multilayers of proteins have been investigated before. , But floating multilayers of self-assembled polyelectrolytes, as presented in the following, have, to our knowledge, not yet been described in the literature. In the following we will show that polyelectrolyte multilayers can be prepared in a controlled way at air/water interfaces and their formation can be monitored by ellipsometry.…”