Engineering Research Equipment: A Modified STM/AFM for Complex Fluid Investigations

The proposal requests equipment to upgrade the scanning tunneling and atomic force microscopic capabilities in the PI's laboratory. The PI currently possesses a Nanoscope II AFM/STM. He proposes to construct a sealed chamber to contain the instrument that will allow constant temperature control, and will permit experiments to be undertaken at low vacuum and under a clean gas such as nitrogen or at a fixed humidity. He also proposes to upgrade the Nanoscope II AFM/STM to a Nanoscope III; the upgrade instrument will allow for a larger scanning field while still maintaining excellent molecular resolution, and will also allow for the measurement of frictional forces as well as normal forces at the cantilever tip. The PI also requests funds for the purchase of a image analysis system independent of the Nanoscope software which will enhance the visual inspection of images, and will enable better quantification of structure characteristics such as periodicity. The PI uses the AFM/STM apparatus primarily to image self assembled monolayer and bilayers of amphiphillic molecules at fluid-fluid and fluid-solid interfaces with nanometer scale resolution. The research activity of the PI in this area is of the highest quality, he has produced several notable achievements such as the identification of a ripple phase for the biological surfactant DMPC. The fundamental imaging studies of bilayers and monolayers will lead to a better understanding of the relationship between the chemical structure of an amphophil and the structures it forms in self assembly. This information is of importance in cell membrane research, and in the research on the technological applications of Langmuir-Blodgett films. The upgrade for the existing equipment will significantly improve the quality and reproducability of the PI's studies. With the environmental control upgrade, experiments in clean atmospheres can be undertaken which will remove capillary force effects arising from pendular bridges which can form at the cantilever tip.