Brian G. Moore

Augustana College (SD)

Research Information (Source Code)

Spring 2008 Chemistry Seminars

TEACHING SPECIALTIES

General Chemistry
Physical Chemistry

RESEARCH INTERESTS

Surface Science
Monolayers

Structure of Liquids

Research Abstract:

My general area of interest is the the study of interfaces, especially as they relate to liquids (liquid interfaces or liquid films on solid surfaces) and the thermodynamics of phase transitions. I am currently working on two projects in these areas, both of which have a role for undergraduate student participation.

Computer Simulations of Liquid Clusters:

Computational power is becoming more and more inexpensive. It is now possible to easily simulate on a personal computer the dynamics of systems of particles up to a few hundred in number. The system I have been studying is that of an isolated cluster of atoms interacting through a Lennard-Jones interatomic potential. We can observe the motion of the atoms and probe the structure of the cluster after the simulation reaches a steady state.

This system is of interest in surface science because a small cluster has a large fraction of its atoms on or near the surface. By varying the temperature, the cluster can be seen in liquid or solid states and the transition between these states may be studied. A particular interest of mine is how the properties of the cluster (density, diffusion rate, etc.) depend on the location within the cluster. Once we have carefully observed these properties under a variety of conditions, it may be possible to construct a model of the structure of the interface, which may be extended to other systems with interfaces.

Atomic Force Microscopy of Surfaces and Surface Films:

The atomic force microscope (AFM) is an instrument which measures the detailed structure of a surface by scanning a very small tip accross the surface. Related to the more famous scanning-tunneling microscope, the AFM is one of a whole family of scanning probe techniques which are now becoming commercially available.

Certain substances will form a monolayer--a film with the thickness of one molecule--when spread on a surface. These monolayers are in a sense two-dimensional systems. For example, one may observe 2-D liquid and solid states in the films. I am just beginning work using the AFM to observe in detail the structure of monolayers deposited on solid surfaces. From other kinds of experiments (fluorescence microscopy) it is known that under certain conditions the film is homogeneous or in a single phase state, while more often the film heterogeneous, with coexisting domains of liquid and solid. The conditions under which these kinds of films form will be explored. The ability to produce a single, homogeneous film is of interest in applications where the properties of the surface are important such as adhesion, friction, etc.