Theodore Eugene Madey - US grants

This proposal brings together an interdisciplinary group of investigators from the fields of surface physics, surface chemistry, materials science, and ceramics engineering to study fundamental properties of oxide surfaces and their interactions metal overlayers. This research is relevant to current and future technology. The spectrum of applications of oxide materials includes ceramic materials with desirable properties for wear or structural use, amorphous oxides for fiber optics and communications, chemical and biological sensors, composites, catalysts and the new high temperature superconducting materials. The goal of the research is to identify and understand the key surface properties that affect the adsorption, nucleation, and growth of metal overlayers on oxide surfaces. The major scientific emphasis will be on (1) metal overlayer formation on well characterized oxide surfaces, (2) metallization of a structural oxide, and (3) metallic adsorption and overlayer growth on amorphous oxides and silicates.

A number of important surface analytical tools rely on an understanding of the transmission of ions through solids. This research project, supported by the Analytical and Surface Chemistry Program, is designed to explore the fundamental scattering and charge transfer processes that influence ion transport through solids having different chemical and electronic properties. Electron stimulated desorption of ions from substrates overlayed with thin films of metal and metal oxide will be used to probe the transmission of ions through these layers. Ion angular distributions, yields, and ion charge exchange processes will be measured for a range of different thin film overlayers. The understanding obtained from these studies will impact surface analysis methodology as well as various material processing technologies using ions. The detailed interactions of ions with solid surfaces are the focus of this research project. Using electron stimulated desorption of ions through carefully controlled thin films of various materials, the fundamentals of the ion-solid interaction will be probed. This information will be useful for the development of surface analytical tools, and in the ion processing of solid surfaces.

This award will provide funding for the renovation of research space in the Nuclear Physics building located on the Busch Campus of Rutgers University. Constructed in 1963, the structure was previously dedicated for nuclear research activities. However nuclear research is no longer conducted in the building, and the vacated space will become available for the Laboratory for Surface Modification (LSM). The LSM is a multidisciplinary laboratory composed of faculty, postdocs, and students from five academic departments: physics, chemistry, ceramics, materials science and electrical engineering. Research at the LSM focuses on advanced developments in the science and engineering of surfaces and thin films. Presently, individual LSM laboratories are dispersed throughout the Physics building and five other buildings on the campus. ARI funds will be used for substantial renovations to laboratory space, including the installation of new walls, partitions, and upgrading the electrical, HVAC, and plumbing systems. Moving the LSM to this building will benefit the program by relieving overcrowding, and by providing a central location to house individual labs and shared facilities. The relocation will produce enhanced focus, visibility and identification of research, fostering new opportunities for the education of students, collaborative interactions between researchers across traditional departmental boundaries, and for the expansion of interactions with high technology industries.

This research project, in the laboratory of Professor Ted Madey at Rutgers University, addresses questions of the energy transfer and charge exchange in the interaction of very low energy ions with various surfaces. Support is provided by the Analytical and Surface Chemistry Program to probe the interaction of low energy atomic and molecular ions with overlayers of inert gases, thin film metals and oxides, and condensed molecular layers. Ions are formed at low energies by electron stimulated desorption, and the energy distribution and identity of emitted ions is probed as a function of overlayer composition and thickness. Experimental results will be compared with calculations which simulate these processes. This information is basic to our understanding of many ion based surface analysis techniques, as well as the dynamics of radiation chemistry and low energy plasma processing of materials. The interaction of low energy ions with surfaces is crucial in the application of analytical methods using ion probes of surface structure and composition, as well as in the interaction of low energy ions in materials processing and in radiation chemistry. This research project explores the detailed mechanism of the interaction of low energy ions with a variety of surfaces, with the goal of obtaining a molecular level understanding of these mechanisms. Detailed experimental measurements will be coupled with calculational studies of these processes.

This project of Professor Theodore Madey of Rutgers Unievsrity, sponsored by the Analytical and Surface Chemistry, supports travel and participation costs for graduate students and young faculty to attend the Eighth International Workshop on Desorption Induced by Electronic Transitions (DIET 8) to be sponsored by Rutgers University 27 September- 1 October 1999, and held at Long Branch, New Jersey. Topics to be covered in the Workshop include basic mechanisms and theory, electroncally induced surface chemistry, semiconductor processing, ion-induced desorption, gas-phase processes such as core excitation and electron attachment, DIET processes in scanning probe microscopies, formation of negative ions at surfaces, laser-induced desorption, and desorption of particles from insulating and condensed layers.

An international group of researchers is scheduled to attend this workshop on desorption induced by electronic transitions (DIET 8), with lecturers from France, Germany, Sweden, Japan and Canada, along with several prominent US researchers. The DIET workshops are held every 2.5 years. The last two meetings were 1997 (Ambleside, UK) and 1994 (Krakow, Poland). This will be the first DIET workshop to be held in the US in the last 7.5 years, and therefore represents a unique opportunity for interaction of US graduate students and young faculty with their colleagues from around the world. The process of desorption from surfaces is central to the areas of photochemistry and semiconductor processing.

This award from the Instrumentation for Materials Research program will enable Rutgers University to acquire a variable temperature scanning probe microscope (scanning tunneling microscope and atomic force microscope, or STM/AFM) with spectroscopic capabilities for shared use in the Laboratory for Surface Modification (LSM) at Rutgers University. The LSM is a multidisciplinary laboratory with research in many areas in the science and engineering of surfaces and thin films. The instrument will be used, in conjunction with other techniques, for several different projects. These include imaging and characterizing charge stripe phases in highly correlated materials, roughening, structural and electrical properties of ultra thin gate oxides for microelectronic applications, and vacancy diffusion, quantum size effects and nano-faceting of metal surfaces and ultrathin metal films. Rutgers will also integrate the SPM into materials education and outreach programs, including developing some web-based classroom training modules. The latter activity will link research-active postdocs and graduate students with middle and high school students and their teachers, and with undergraduates.
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This award from the Instrumentation for Materials Research program will enable Rutgers University to acquire a variable temperature scanning probe microscope (scanning tunneling microscope and atomic force microscope, or STM/AFM) with spectroscopic capabilities for shared use in the Laboratory for Surface Modification (LSM) at Rutgers University. The LSM is a multidisciplinary laboratory with research in many areas in the science and engineering of surfaces and thin films. The instrument will be used, in conjunction with other techniques, for several different research projects that require state of the art imaging of surfaces at the atomic scale. Today, the need for truly atomic level imaging of surfaces is compelling. Scanning tunneling microscopy and other scanning probe techniques have revolutionized surface science and been applied to a wide range of problems related to interfaces. The SPM will be integrated into materials education and outreach programs, including developing some web-based classroom training modules. The latter activity will link research-active postdocs and graduate students with middle and high school students and their teachers, and with undergraduates.
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Investigation of the mechanism of fluorine and chlorine anion emission from adsorbed layers of halogenated hydrocarbons irradiated by electrons forms the focus of this research project supported by the Analytical and Surface Chemistry Program. Professor Theodore Madey and his coworkers at Rutgers University are examining the enhanced emission of Cl- and F- from physisorbed layers of CFC's in contact with water, ammonia, or non-polar co-adsorbates. A series of measurements is being carried out to elucidate the mechanism of this enhanced emission, and the connection this may have to the heterogeneous chemistry of ozone in the stratosphere. Electron stimulated ion angular and energy distributions are measured under a variety of conditions of surface temperature, co-adsorbate polarity, and incident electron energy in order to provide mechanistic understanding of the fundamental surface processes of ion emission.

When adsorbed layers of chlorofluorocarbon compounds are irradiated with low energy electrons, significant amounts of chlorine and fluorine anions are desorbed. In the presence of certain polar co-adsorbates such as water and ammonia, this emission is dramatically enhanced. This research project examines this effect with a series of ion angular and energy distribution measurements. Connections of this effect with problems of ozone depletion in heterogeneous stratospheric chemistry are made in this research. The results of these studies, in addition to providing considerable fundamental insight into ion processes at surfaces, may help to understand stratospheric ozone depletion processes

Rutgers University will build a facility for very-high resolution (<1 nm) depth profiling of light elements in thin films using narrow nuclear resonances. This facility will be installed at an existing accelerator at the Laboratory for Surface Modification (LSM) at Rutgers University and will complement several existing depth profiling techniques there. It will be the first facility of its kind in the US. The experiments will utilize several different extremely narrow (<10 eV) nuclear resonances. By scanning the incident ion energy, the dept from the surface at which the nuclear reactions occur can be varied and information about the depth distribution of the species under study is obtained. Examples of the diverse applications to be pursued include studies of diffusion, segregation and breakdown in ionic conductors, diffusion of sodium in minerals in interplanetary space, novel materials for high performance computer chips, and the long term stability of materials used for storage of nuclear waste. Users outside the LSM, from Rutgers University and elsewhere, can also access this facility, primarily through collaborations. The educational program includes weekend hands-on work in the laboratory by high school students; computer based experiments by undergraduates and summer workshops for senior materials scientists. Research using ion beams is attractive to a wide range of students because of the technical sophistication of these experiments, the "straightforward" (classical, model independent) quantitative data analysis and the close coupling to very real modern technical applications.
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Rutgers University will construct a novel facility for depth profiling of light elements by ion beam analysis using narrow nuclear resonances. This will be the first facility for nuclear resonance depth profiling in the US. In many scientific applications, one needs to quantify the number of atoms as a function of their distance from the surface. Examples of such diverse applications, described in the proposal, include studies of diffusion, segregation and breakdown in ionic conductors, diffusion of sodium in minerals in interplanetary space, novel materials for high performance computer chips, and the long term stability of materials used for storage of nuclear waste. The facility will utilize several different extremely narrow nuclear resonances. Depth profiling will be accomplished by changing the incident ion energy, so that the depth at which nuclear reactions occur is varied continuously. The educational program includes high school students, undergraduates and also senior materials scientists. Research using ion beams is attractive to a wide range of students. The technical sophistication of these experiments, the "straightforward" (classical, model independent) quantitative data analysis and the close coupling to very real modern technical applications makes it possible to attract promising students to science.

This IGERT program at Rutgers University, focused on integratively engineered biointerfaces, will be an intimately collaborative effort of 32 selected faculty from graduate programs in Molecular Biosciences, Physical Sciences (Physics, Chemistry & Chemical Biology), and Engineering (Biomedical Engineering, Ceramics and Materials Engineering, Chemical and Biochemical Engineering, Mechanical and Aerospace Engineering).

Intellectual Merit: The program derives strength from the highly cross-disciplinary nature of over fifteen research project areas identified at the cutting edge of the field of biointerfaces, and programmatic partnerships with five strategic centers of excellence to promote cohesive access for the IGERT community to state-of-the-art research infrastructure. A wide range of thesis project themes is planned for the IGERT trainees, developed around three research and educational thrusts, (1) living cell-based interfaces, (2) microengineered and nanoengineered biointerfaces, (3) biosensing and bioresponsive interfaces. The five major partnering Centers for the IGERT program are: Keck Center for Collaborative Neuroscience, Center for Nanomaterials Research, New Jersey Center for Biomaterials, the Laboratory for Surface Modification, and the Rutgers Center for Computational Design. The educational core of the proposed IGERT program will intimately support the research program, and includes graduate courses in the integrative areas of biointerfacial engineering, as well as course modules on responsible conduct of research, technical communications, entrepreneurship and effective teaching/learning methods.

Broader Impact: The IGERT curriculum is designed to foster a community featuring the next generation of biointerfacial and biomaterials engineers by offering IGERT graduate fellows a range of interactive experiences at multiple levels: multi-disciplinary coursework, lab rotations in two cross-cutting research groups, biannual participation in symposia, and participation in a national/international conference resulting in a white paper. To maximize its impact, the IGERT program will offer varied programmatic pathways to promote diverse modes of professional development of IGERT graduate fellows: (1) Summer research internships at selected international sites for academically inclined students; and (2) Translational research and industrial summer internships for students interested in industrial and entrepreneurial careers. Through a partnership with the Robert Davis Learning Institute of the Rutgers Graduate School of Education Institute, the IGERT program will establish a COLTS (Community of Learners and Thought Shapers) program, inspired by communication-driven cognition models, to encourage IGERT fellows to develop as learners by dynamically communicating their research on integratively engineered biointerfaces.

IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries. In this sixth year of the program, awards are being made to institutions for programs that collectively span the areas of science and engineering supported by NSF.

Abstract
CHE-0315209
Madey/Rutgers

With the support of the Analytical and Surface Chemistry Program, Professor Madey and his coworkers in the Rutgers University Department of Physics and Astronomy are examining electron driven chemistry of halogenated molecules adsorbed on surfaces and in thin films of water, ammonia, and other species. Emphasis on the role of coadsorbed solvent molecules on mechanisms of reaction and rates of reaction are being examined. Time of flight electron stimulated desorption ion angular distribution (TOF-ESDIAD) measurements are used to characterized the electron stimulated desorption and dissociation processes for halogenated molecules in the presence of polar and non-polar solvent species in the condensed thin films. Fundamental mechanisms by which the coadsorbate influences electron induced reactions are examined. Information from these studies is useful for understanding mechanisms of ozone depletion and environmental remediation.

Chemical reaction processes driven by electron irradiation are the focus of the research of Professor Madey and his coworkers. By measuring the angular distribution of ion products of electron irradiation of thin films and surfaces, information about the mechanisms of desorption and decomposition of adsorbed halogen containing species is obtained. This information is important in developing an understanding of environmental and atmospheric chemical processes involving halogen containing molecules.

Short technical abstract:

The ability to quantify the concentration of hydrogen and low mass atoms while determining their bonding configuration and depth profile is needed for a wide range of applications in science, engineering and industry. Hydrogen is almost always present in thin films, is often concentrated at surfaces and interfaces, and can affect material properties in a substantial manner. For example, hydrogen can either improve or degrade the performance of microelectronic devices by passivating or introducing defects at interfaces. In other classes of materials, hydrogen degrades mechanical properties and can lead to embrittlement. Hydrogen is also a critical element for future energy use. Hydrogen, carbon, oxygen and nitrogen are the basic elements of polymers, organic, pharmaceutical and biological molecules. Quantitative determination of hydrogen and low mass element concentration is therefore essential for full characterization of thin films and bio-interfaces, which constitute the building blocks for biotechnology.
We propose to construct an integrated ultra-high vacuum chamber that combines in-situ infrared absorption spectroscopy (IRAS) with NRA and ERDA to detect hydrogen, and glancing angle detection (GAD) to detect other low-mass atoms. When combined with the sensitivity of IR spectroscopy to the bonding state of hydrogen and light atoms, ERDA will provide not only critical accurate quantification but also speciation of the types and amounts of hydrogen and other low mass species, thus making it possible to greatly accelerate our ability to understand the basic science behind their materials chemistry, and to yield better control of these species in practical applications. The purpose of the proposed construction project is to provide quantitative chemical and structural information of surfaces, interfaces and thin films (inorganic, organic, and biological) in which hydrogen and light atoms play an important role. The new facility will have a wide-reaching influence on research and education programs within and outside Rutgers spanning a number of areas, including biology, bio-catalysis, drugs synthesis, nano-electronics, silicon-on-insulator (SOI) fabrication, and H-storage.

Short technical abstract:

Hydrogen is arguably the most important element in nature; it is part of all fuels and soft matter (plastics, glue, etc.), plays an important role in the properties of hard matter (metal embrittlement, drugs), and is an important source of energy. To understand its role and to take full advantage of its properties, precise measurement methods must use to detect and characterize hydrogen. While is chemical state (bonding configuration) can be determined using infrared spectroscopy (a method to measure the characteristic vibrations of hydrogen), it is much more difficult to measure the total amount of hydrogen within a material, or at an interface. The best method is to send high energy ions into the material of interest and to measure the number of hydrogen atoms ejected (due to the strong collision between the heavy incoming ion and lighter hydrogen atom inside the material). We propose here to construct an integrated system that combines infrared spectroscopy with various methods based on ion scattering to detect both the chemical nature and quantity of hydrogen in materials. This facility will make it possible to greatly accelerate our ability to understand the basic science behind materials chemistry, and to yield better control of hydrogen for various applications. The new facility will also have a wide-reaching influence on research and education programs within and outside Rutgers spanning a number of areas, including biology, bio-catalysis, drugs synthesis, nano-electronics, microchip fabrication, and hydrogen storage.