Observation of a liquid-to-layered transition in thin liquid films when surface and interface regions overlap.
We have used x-ray reflectivity to study the coupling of surface and interface layering in a molecularly thin normal liquid [tetrakis(2-ethylhexoxy)silane (TEHOS)], as a function of temperature and film thickness. The best fits to the data were obtained with an electron density model that consists of a uniform density component superimposed upon molecular-scale density oscillations (layers). The two types of layer profiles were observed to vary with temperature from 187-286 K . The amount of material in the molecular layers increases as that in the uniform density layer decreases, with the onset of liquid-to-layered transition occurring at a total film thickness of approximately 40 A (about twice the bulk correlation length of TEHOS).
Pohang Accelerator Laboratory and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
Dong Ryeol
DR
Lee
Pulak
P
Dutta
Chung-Jong
CJ
Yu