The properties of associating fluids in contact with adsorbing surfaces are essential for the control of many processes of current industrial and scientific interest. Potential applications are diverse. Despite the need for a molecular understanding of interfacial properties, only in the past a few years have simple, accurate theories been developed for even simple fluids. Our group has developed a new density functional theory which applies the weighting from Tarazona's hard sphere density functional theory to Whertheim's bulk first-order perturbation theory to investigate inhomogeneous pure associating fluids confined between hard walls. This theory has been shown to be in good agreement with computer simulation results. In this work, we extend this promising theory to binary mixtures of hard spheres and associating fluids, and apply the mixture theory to non-additive hard spheres. We have accurately predicted phase separation, critical temperature and structural properties for this model. We then extend this theory to describe the properties of associating fluids near active surfaces. Metropolis Monte Carlo computer simulations are performed for one-sited (dimerizing), two-sited (linear chain forming) and four-sited (cluster forming) molecules near active surfaces. Our theory compares favorably with simulation results for a wide range of fluid density and bonding energy for surface coverage, density profiles and faction of monomers.

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This work describes the development of a unique capability for electron beam excitation of hot vapors combined with VUV spectroscopy. The first result obtained with this new facility was the observation of emission from the triatomic rare gas halide Ne$\sb 2$F* at 132 nm. An investigation of the kinetic processes for both Ne$\sb 2$F* and its precursor NeF*, which emits at 108.5 nm, was performed. Several relevant rate coefficients were determined. It was concluded that this system is analogous to the Ar-Cl system, in that it predissociates due to excited halogen dimer formation. Therefore the realization of NeF* or Ne$\sb 2$F* laser action would be difficult due to F$\sb 2$* production. NeF* fluorescence, however would be more likely to achieve gain due to its higher stimulated emission cross-section.

As semiconductor technology continues to miniaturize, surface phenomenon become prevalent. Clusters can be considered as model compounds of the surface in free space. By performing experiments on clusters, it is equivalent to focussing on local sites of the bulk surface, and building it one atom at a time. The development of supersonic beams of clusters has proved to be one of the most powerful methods in preparing the "nano" state, the intermediate range between atomic and the macroscopic description of matter. Fourier Transform - Ion Cylcotron Resonance (FT-ICR), a mass spectrometry technique, coupled with these cluster beams was used to study gallium arsenide, a well-utilized semiconductor. The complexity of isomers and the stoichiometric distribution within a given cluster size has been simplified using mathematical methods for signal deconvolution. By studying reaction parameters with ammonia, gallium arsenide clusters proved to be an adequate comparative model for real surfaces. Furthermore, local density theoretical calculations, which are feasible on these small clusters, provided a corroborative and predictive proving ground for this system.

We present evidence that magainin I, a 23 residue antibiotic peptide, undergoes a concentration dependent phase transition in synthetic lipid multilayers. Using oriented circular dichroism (OCD) we show that in low concentrations, magainin forms $\alpha$-helices lying parallel to the membrane surface. When the concentration becomes greater than a lipid specific value, the magainin undergoes a conformational change to a yet unidentified state. The state of the system at concentrations above the critical concentration shows that this transition cannot be explained by the micellar effect. Correlations between our results and liposome leakage experiments indicate that this transition is responsible for magainin's antibiotic action.

Field emission from carbon nanotubes has been measured. Typical values are 100-1000 nA at a nanotube bias of $-$80V. The amount of field emission is found to depend strongly on the state of the nanotube tip. This should serve in future work as a good indicator of tip condition. It is believed that open tip nanotubes unravel at their ends while field emitting to form a carbon chain. An atomic chain being the ultimate geometry for a field emitter, nanotube tips may have applications for monoenergetic electron sources, electron microscope field emitters, and electron holography.

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