At compact monolayer coverage the anisotropic rodlike molecules of palmitic acid, aligned parallel to each other and perpendicular to the monolayer film, are insensitive to wavelength dispersion relative to a water substrate. The relative absence of dispersion of the monolayer film makes it possible to obtain sufficient data to characterize the three unknowns of palmitic acid: the real refractive indices parallel and perpendicular to the plane of the film and the film thickness. Other nonabsorbing thin-film-substrate systems should lend themselves to similar analysis (where the dispersion of the film is relatively less than that of the substrate); particularly since automated, wavelength-tracking ellipsometers are coming into greater use.
© 1978 Optical Society of America
G. T. Ayoub and N. M. Bashara, "Characterization of a very thin uniaxial film on a nonabsorbing substrate by multiple wavelength ellipsometry: Palmitic acid on water," J. Opt. Soc. Am. 68, 978-983 (1978)