Lehigh University has a long history of research and investment in studies of the science and technology of surfaces and interfaces. This effort, along with more recent major commitments to advanced materials and nanotechnology, has often necessitated pushing the frontiers of surface analysis. An accurate, quantitative knowledge of the surface layer composition or monolayer film coverage at a solid surface is required in a wide range of applications such as catalysis, sensors, fuel cells, microelectromechanical systems (MEMS), coatings, adhesion, self-assembled monolayers (SAM), membranes, and biocompatibility to design advanced materials. This proposal seeks funds for acquisition of a high-sensitivity low energy ion scattering (HS-LEIS) spectrometer that will meet these needs and enable new research. LEIS is known as the only technique that provides quantitative elemental analysis of the outermost, top layer at surfaces. This can be compared to x-ray photoelectron spectroscopy (XPS or ESCA) that furnishes near-surface (top few nm) information. A new instrument with unprecedented capability has just become available as the QTAC 100 system from ION-TOF. Specifically, a unique double toroidal electrostatic energy analyzer based on the advanced Calipso technology provides 3,000 times higher sensitivity than conventional ion scattering spectrometers. This spectrometer will be integrated into a system that will enable a wide range of studies of surface spectroscopy, surface imaging and non-destructive depth profiling. This system also has superior capabilities for analyzing insulating samples and for serving many users by incorporating a rapid sample introduction loadlock and sample transfer system fully integrated into the system.
The intellectual merit of the proposed activity. The fundamental research and development activities performed by using this new instrument will push the limits of understanding of key technological problems involving surfaces and interfaces. In particular, it will enable previously unobtainable information about the elemental composition in the topmost surface layer of a wide range of practical materials. For example, it will play a key role in an emergent theme at Lehigh on "Designed Active Interfaces", where active interfaces refer to surface phases that undergo dynamic molecular and/or electronic structural transformations when placed in reactive environments. Research is proceeding in three thrusts: heterogeneous catalysis, optical and biosensors, and new functionality glasses. The requested HS-LEIS system can analyze a broad range of samples, including metal single crystals, semiconductor wafers, powders, insulators, glasses, polymers, biomaterials, and rough samples, and analysis can be carried out at high temperatures. Clever design of this instrument also enables depth analysis with extreme resolution (layer-by-layer) up to a depth of 10 nm, charge compensation for insulators, sample heating in controlled environments, and secondary electron imaging.
Broader impacts resulting from the proposed activity. The HS-LEIS instrument will be the only one of its kind in the U.S., and it will be the first one in the world to be dedicated solely to research. This will provide opportunities in cutting-edge research at Lehigh, and also for a broader community. The Center for Advanced Materials and Nanotechnology (CAMN) at Lehigh operates and maintains the Surface Analysis Facility, which has the only Scienta ESCA 300 instrument in the U.S., and the Nanocharacterization Laboratory, with the largest academic collection of electron microscopes in the U.S. These facilities bring many undergraduate and graduate students from universities, along with researchers, technicians, and engineers from government and industrial laboratories to Lehigh each year. The HS-LEIS system will enable this large community to work with this state-of-the-art equipment and address new research projects. Also, the instrument will be available to international visitors to the NSF International Materials Institute. It will be utilized immediately in several science and engineering courses at LU, ongoing REU programs, and will be showcased at the annual Lehigh Microscopy School. Outreach will also include high school students participating in the annual summer Materials Camp, along with involvement in activities of the Materials Instructional Technology Lab - a K-12 outreach program run by CAMN.
