Ongoing Projects

Metal Carbides

Transition metal carbides are unique with respect to both their chemical and physical properties. Chemically, some transition metal carbides display reactivity and catalytic activity similar to platinum. Physically, these materials are extremely hard and possess high melting points.

LEED and STM of TiC (100)

The surface chemical reactivity of a wide range of functionalities is being explored on surfaces of titanium carbide and vanadium. Particular attention is given to the relationship between the local structure, the electronic structure, and the measured reactivity.

The surface electronic structure of metal carbides is being measured with electron spectroscopy and correlated with the chemical and tribological properties of the surface. The results of these studies are relevant to the development of hard coatings for use in Aerospace applications.

Metal Oxides

The local order and crystallinity of a metal oxide surface is being investigated with atomic force microscopy and correlated with the chemical reactivity of the surface with molecular adsorbates such as oxygen, water, and methanol as measured by time-of flight mass spectroscopy and x-ray photoelectron spectroscopy. The results of these studies are relevant to the development of gas sensors and fuel cell technologies.

A topographic image of MgO (100) collected by atomic force microscopy reveals the terrace structure of the oxide surface on the nanometer scale following annealing treatments in ambient pressure of oxygen at temperatures above 1250 K.

Nanometer scale metal particles

These have demonstrated size-dependent chemical and catalytic properties, however often suffer from instability and sintering at elevated temperatures. Atomic force microscopy is being used to follow the changes in metal particles on insulating oxide supports as a function of temperature. A central aspect of this research explores methods of controlling surface diffusion and increasing particle stability

Aqueous Biomimetic Lubrication

The correlation of molecular structure and the physical interfacial properties of molecularly thin coatings lies at the heart of a fundamental understanding of wetting, adhesion, and friction. This correlation is being probed on a nanometer scale using atomic force microscopy and a range of spectroscopic tools.

This approach is currently being applied to adsorbed, water-soluble polymer brushes.The aim is to develop synthetic lubricants that mimic joint lubrication within the human body. Unlike most industrial applications involving oils and greases, joints are lubricated in an aqueous environment. A benefit of water-based lubrication is that it’s less flammable and more efficient in controlling heat than oil-based lubrication. This also represents an opportunity to design environmentally friendly lubricants.

A schematic representation of the electrostatic adsorption of poly(L-lysine)-g-polyethylene glycol on an oxide support. Recent studies have documented the structure and adsorption properties of this polymer brush structure and highlighted its similarity to biomolecules found within articular cartilage.