Technical Summary: X-ray photoelectron spectroscopy (XPS) is widely used as an analytical technique to determine the nature of the near-surface region of a material. Shifts in the core level binding energies of atoms at or near the surface of a material can reveal changes in oxidation state, surface potential or band bending, chemical or physical inhomogeneity, or dynamic response (i.e., screening) that are distinct from those of the bulk of the material. However, a growing number of modern applications employ materials in complicated structures that are laterally inhomogeneous and thus it is critical to perform XPS in a spatially resolved manner, along with high photon flux, and high energy resolution. Examples, that are currently active research areas at Rutgers include the study of: (i) transition metal ions and their diffusion in ZnO for room temperature spintronics, (ii) surface modification of organic single crystal surfaces, (iii) surface functionalization and characterization of novel nanocrystals used to enhance biomolecule imaging, (iv) surface characterization of plasma-treated and chemically-modified polymer films for cellular and related bioactivity studies, and (v) interface properties of nanoscale self-assembled solid state systems. The Rutgers Laboratory for Surface Modification (LSM) is a multidisciplinary research center that hosts a comprehensive set of facilities used to examine surfaces, interfaces, thin films, and nanoscale materials, and has strong collaborations with state-of-the-art research and development laboratories around the world. A gap in our suite of tools is lack of a modern high resolution XPS system that can adequately address the key issues in the study of modern materials systems. The state-of-the-art instrumentation requested in this proposal would replace a 20-year-old machine and will significantly strengthen our capabilities by enabling high energy resolution studies, in parallel with high resolution lateral imaging and depth profiling. These features are central to the diverse research and education activities both within Rutgers as well as the regional community.
Non-Technical Summary: Materials interact with their surroundings through their surfaces. Very often, the chemical or physical environment of surface atoms is significantly different from those of the bulk A powerful way to probe surface properties is to expose a material to X-rays of a specific wavelength and study the electrons that are emitted from surface. As only electrons that originate from the first one or two nanometers of the surface are able to escape the material, this technique is very surface sensitive. Moreover, these electrons escape with well-defined energies that not only depend upon the atomic species, but also exhibit small variations depending on the environment of the atom. The study of these electrons, known as X-ray photoelectron spectroscopy (XPS), enables one to determine the chemical and physical state of these near-surface atoms. In modern materials systems, such as nanoscale crystals used to enhance imaging of biological systems, or potentially revolutionary semiconductors made entirely of organic molecules, the atomic environment in one region of the surface can differ from that of another region. Therefore, it is critical to perform XPS studies in a spatially resolved manner. The Rutgers Laboratory for Surface Modification (LSM) is a multidisciplinary research center that hosts a comprehensive set of facilities used to examine surfaces, interfaces, thin films, and nanoscale materials, and has strong collaborations with state-of-the-art research and development laboratories around the world. A gap in our suite of tools is lack of a modern high resolution XPS system that can adequately address the key issues in the study of modern materials systems. The state-of-the-art instrumentation requested in this proposal would replace a 20-year-old machine and will significantly strengthen our capabilities by enabling high energy resolution studies, in parallel with high resolution lateral imaging and depth profiling. These features are central to the diverse research and education activities both within Rutgers as well as the regional community.
