Surface light-scattering measurements have been carried out on thin asymmetric films of pentane on water. We vary the film thickness ℓ over a wide range (10-9 m < ℓ < 10-5 m). Compared with the ripplons wavelength 1/q, thick films of pentane (ℓ ≫ 1/q) display the same power spectrum as a pure pentane–vapor interface: a single peak. When thinning the film down to ℓ ≈ 1/q, hydrodynamic coupling between the layers of the interface is revealed by the appearance of a second peak beside the first one. We describe the thickness dependence of the two coupled modes through variations of the positions, the widths, and the amplitudes of both peaks.
© 2001 Optical Society of America
Original Manuscript: December 8, 2000
Revised Manuscript: April 23, 2001
Published: August 20, 2001
Denis Fenistein, Gerard H. Wegdam, William V. Meyer, and J. Adin Mann, "Capillary waves on an asymmetric liquid film of pentane on water," Appl. Opt. 40, 4134-4139 (2001)