Complex molecular layering of OH-terminated perfluoropolyalkylether films over amorphous carbon surfaces has been observed using spatially resolved microellipsometry. The first layer is diffusive in nature, and the subsequent layers exhibit sharp steps of about twice the thickness of the first layer. This behavior, characteristic of a coexisting two-dimensional gas, with cohesive, liquidlike multilayers, is in clear contrast with that of the CF 3 -terminated analog, which shows a smooth diffusive profile. In this particular case, spreading, for thickness greater than one monolayer, can be exactly described by a Poiseuille flow in a disjoining pressure gradient originating solely from van der Waals interactions. For both types of polymers, diffusion rate reaches a maximum at full monolayer coverage, and decreases in the submonolayer regime. Spreading for both types of polymers unambiguously follows a t 1/2 time dependence. ͓S1063-651X͑99͒05601-9͔

Spreading of perfluoropolyalkylether thin films on amorphous carbon surfaces has been studied by scanning microellipsometry. Two types of perfluoropolyalkylethers with the same main-chain structure and various molecular weights (between 1000 and 6000 g/mol) were used: Zdol, with OH functional end groups, and Z, with nonfunctional CF3 groups. For Zdol, the thickness of the molecular layers in the spreading profile increase as Mn0.6, where Mn is the mean molecular weight, with the second layer being nearly twice as thick as the first layer. This layered structure was not observed for Z in the molecular weight range under study. As expected, the thickness-dependent diffusion coefficient D(h) was found to decrease with increased molecular weight. Possible molecular conformations near the solid surface are discussed. The spreading of binary blends of Zdol–Zdol, Z–Z, and Zdol–Z were also studied. The results show that the spreading of the binary blend of the same kind of polymer with different molecular weight behaved like that of a lubricant with an intermediate molecular weight. The diffusion coefficient of a blend was found to obey the additivity of viscosity. For Zdol–Z blends, however, the faster moving Z molecules migrate through the network of the slower moving Zdol molecules, and form a monolayer ahead of Zdol.

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The ability to look into an electronic display from any direction, walk arotind it, and see real 3D information being displayed is a dream-come-true technology for those who work with volumetric data sets. REALIZING 3D VISUALIZATIONUSING CROSSED-BEAM VOLUMETRIC DISPLAYŜ^^^^^^ ince we live In a three-dimensional world, we continously interact with 3D H " objects both near and far away. The human body can extract enormous amountŝ^^^^^^ of information about its environment from a single sensory input: sight. Becausê^^^^^ we obtain over 70% percent of our sensory input visually, we judge shape, size, A ^M distance, relative position, movement, speed, and a host of other physical attrih-^^^^^^^^ utes using the binocular vision provided by our two eyes. In addition, the human visual system works in real time, enabling us to interpret a 3D world that is changing rapidly. Our incredible ability to perceive depth through stereopsis, motion parallax, focus, and eye convergence is more reliable and useful tban the visual cues pre-they are still flat. In addition, the data is presented sent in current 2D displays using relative size, from a single-user vantage point that prevents superposition, and lighting. viewers from using motion parallax to gain slightly Electronic displays such as the cathode-ray tube different views in order to extract depth informa-(CRT) and the liquid crystal display (LCD) pre-tion. Even stereo display techniques that provide sent visual information on flat surfaces. Despite separate left and right eye images do not provide 1 powerful rendering techniques, such as perspective, users with sufficient depth cues, resulting in a con-2 shading, shadowing, and texturing that have been flict between focus and convergence that ofben < employed to increase the realism of these images, causes unwanted physiological side effects.