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Molecular 'nanowire' structures composed of the charge transfer complex of a bis-tetrathiafulvalene substituted macrocycle and tetrafluorotetracyanoquinodimethane were constructed on mica substrates by employing the Langmuir-Blodgett technique. The nanowires transferred from a dilute aqueous potassium chloride subphase had typical dimensions of 2.5 nm x 50 nm x 1 [micro]m. The nanowires are oriented to specific directions, corresponding to the directions of the potassium-ion array on the mica surface having sixfold symmetry. Such correlation between the nanowires and the substrate surface was also observed when a dilute aqueous rubidium chloride subphase was used. On the other hand, the correlation completely disappeared when the subphase contained divalent cations, indicating that the molecular nanowires orient by recognizing the monocation array on the mica surface. The nanowires formed by the vertical dipping method coexist with the monolayers. Only nanowire structures are, however, observed when we apply the horizontal lifting method. Based on the crystal structure of a related complex, a possible structure of the nanowires is presented. The conductivity of the nanowires was estimated to be of the order of [10.sup.-3] [S*cm.sup.-1]. The nanowires formed specific (regular) structures such as T-shape junctions, suggesting their use in construction of future molecular nanoscale devices.

Frictional characteristics of several types of boundary lubricants were tested using scanning probe microscopy (SPM). These include Langmuir monolayers of stearic acids (STA), their cadmium salts (STCd), self-assembling monolayers (SAMs) of alkylchlorsilanes, and complexes of STA with rigid naphthoylene benzimidazole (x-NBI) fragments. We observed that a Langmuir monolayer deposited on a silicon surface had a very low friction coefficient against a silicon nitride tip (about 0.01-0.05) but also low mechanical stability. SAMs were found to be much more stable but had the drawback of growth in the friction coefficient at high sliding velocities. Composite NBI/STA monolayers were much more stable and were not damaged by the highest normal load applied. The frictional behavior of different monolayers was analyzed in relation to their structural organization (the type of tethering to the surface and packing density). We introduced a figure of merit (FOM) parameter which allowed comparison of frictional properties of very different lubricant materials to those of the supporting substrate. For Langmuir monolayers the FOM increased strongly with surface packing density whereas for SAMs and x-NBI/STA complexes it possessed a maximum at surface densities in the range 3.5-4.5 molecules per [nm.sup.2]. Because of the possibility of tailoring the surface packing density of aliphatic tails in the complexes, they are a promising alternative to both LB films and SAMs. For such composite monolayers, the surface packing density can be optimized to give a desired frictional behavior.

Transmission lines in a multi-chip module, based on polyimide-copper multilayer on ceramic, exhibit low capacitance, reduced propagation effects and reduced propagation delay. Distinct ground geometries, namely continuous solid plane, and meshed ground planes with octagonal and rectangular openings, are used to analyze the influence of thin-film polyimide multilayer on signal transmission. Meshed ground with rectangular openings provides effective impedance, cross talk noise and attenuation trade-off. Meshed ground with octagonal opening provides poor results.

Anisotropy has a substantial effect on the diagonal terms of the matrix and should be considered in design and construction of open, closed, or partially shielded multilayer-multiconductor structures as revealed by their analysis by using the finite difference method. The suitability of this technique for analyzing circuit geometries of microwave integrated circuits, printed circuit boards and in surface acoustic wave applications for frequencies up to 5 to 10 gigahertz is discussed.

Study of calcium arachidate Langmuir-Blodgett films incorporating atomic force microscopy techniques indicates that achiral molecules spontaneously break down to form lattices with chiral packing of opposite hardness. The alkane tail imposes packing constraints, and calcium ion space requirements possibly interact to cause the breakdown of symmetry.

A comparison between chemically and laser etched vias in polyimide reveals the laser etched vias are more suitable for electroless copper plating, as their sidewalls are steeper than those of chemically etched vias. Laser etched vias have no gap between copper and polyimide and can be filled easily with electroless copper. Chemically etched vias are hollow and are incompletely filled during electroless metallization.

The precise optical absorption for axisymmetric chopped-beam laser heating influences the temperature in isotropic multilayer materials. The anisotropic thermal characteristics and the contact resistance between the layers are studied to hypothesize the temperature in the layers. Anisotropic but steady thermal characteristics are revealed, and are independent of the number of layers in the solution, which indicate resistance of contact. A single laser pulse can adopt this experiment when a Fourier transform is used to gauge the frequency components of the laser pulse.

Frequency domain photopyroelectric effect spectrometry (FD-PPES) is a recent spectroscopic technique that may be used to recover depth profiles of optical absorption in thin films on a noncontact and nondestructive basis. In this work a series of well characterized thermally homogeneous samples were prepared that exhibited continuous or discrete subsurface profiles of optical absorption. Multi-frequency FD-PPES measurements made on these samples were compared to theory using a heat transfer model, which we have developed for a multilayer thermally homogeneous absorber. Excellent agreement between experiment and theory was obtained for these model studies. While both phase and magnitude channels of the FD-PPES response give depth profiling information, the phase response is especially sensitive to variations in the subsurface profile of optical absorption. By means of the phase response it is possible to determine the number and spatial positions of absorbers in a series of discrete absorbing layers. The FD-PPES technique has excellent potential for analysis and nondestructive evaluation of polymer films.

The addition of a second hydrophobic end-group to the hydrophilic chromophore prevents molecular inversion during deposition on a solid substrate. This enables the formation of a 'Z-type' head-to-tail structure for films with up to 100 layers. The newly developed process enables the formation of macroscopic non-centrosymmetric order in Langmuir-Blodgett films.

Viscous, laminar, gravitationally-driven flow of a thin film over a round-crested weir is analyzed for moderate Reynolds numbers. A previous analysis of this flow utilized a momentum integral approach with a semiparabolic velocity profile to obtain an equation for the film thickness (Ruschak, K. J., and Weinstein, S. J., 1999, 'Viscous Thin-Film Flow Over a Round-Crested Weir,' ASME J. Fluids Eng., 121, pp. 673-677). In this work, a viscous boundary layer is introduced in the manner of Haugen (Haugen, R., 1968, 'Laminar Flow Around a Vertical Wall,' ASME J. Appl. Mech. 35, pp. 631-633). As in the previous analysis of Ruschak and Weinstein, the approximate equations have a critical point that provides an internal boundary condition for a bounded solution. The complication of a boundary layer is found to have little effect on the thickness profile while introducing a weak singularity at its beginning. The thickness of the boundary layer grows rapidly, and there is little cumulative effect of the increased wall friction. Regardless of whether a boundary layer is incorporated, the approximate free-surface profiles are close to profiles from finite-element solutions of the Navier-Stokes equation. Similar results are obtained for the related problem of developing flow on a vertical wall (Cerro, R. L., and Whitaker, S., 1971, 'Entrance Region Flows With a Free Surface: the Falling Liquid Film,' Chem. Eng. Sci., 26, pp. 785-798). Less accurate results are obtained for decelerating flow on a horizontal wall (Watson, E. J., 1964, 'The Radial Spread of a Liquid Jet Over a Horizontal Plane,' J. Fluid Mech. 20, pp. 481-499) where the flow is not gravitationally driven. [S0098-2202(00)01904-0]

This paper develops a liquid film symmetry correlation and a liquid film thickness distribution model for horizontal annular gas-liquid pipe flows. The symmetry correlation builds on the work of Williams et al. (1996) (Droplet Flux Distributions and Entrainment in Horizontal Gas-Liquid Flows,' Int. J. Multiphase Flow, Vol. 22, pp. 1-18). A new correlating parameter is presented. The liquid film thickness model is based on the work of Laurinat et al. (1985) (Film Thickness Distribution for Gas-Liquid Annular Flow in a Horizontal Pipe,' PhysicoChem. Hydrodynam., Vol. 6, pp. 179-195). The circumferential momentum equation is simplified to a balance between the normal Reynolds stress in the film's circumferential direction and the circumferential component of the weight of the film. A model for the normal Reynolds stress in the circumferential direction is proposed. The symmetry correlation is used to close the model equations. The model is valid for films with disturbance waves, and is shown to be applicable to air-water flows over a range of conditions from low velocity asymmetric to high velocity symmetric annular flows. [S0098-2202(00)02102-7] Keywords: Two-Phase Flow, Annular Flow, Horizontal Gas-Liquid Flow, Liquid Film Thickness Distribution

A polymer film remains effectively thin, even when it is hundreds of atom layers thick, because of the deposition of deuterated polystyrene on the silicon surface. The adsorption of a large number of chains on the surface hinders other chains and results in slow diffusion of polymer chains. Thin film polymers find application in electronics, controlling the alignment of liquid crystals, and high-temperature polymers for insulating layers in integrated circuits.