Faculty advisors are active in the study of the structure, reactivity and thermodynamics of materials in addition to the characterization of their electronic and optical properties. Research groups consist of faculty and graduate students from the Chemistry and Physics Departments who guide undergraduate participants in the program.

Spectroscopic and Thermodynamic Studies of Oil Dispersants at the Oil/Water Interface
Geraldine Richmond, REU Program Director
Oil dispersants have a history of being used to break-up oil spills but as we have witnessed in the recent Gulf oil spill, little is known about their toxicity and their effectiveness in sea water.  Our interest is to contribute to the understanding on a molecular level of how relevant dispersants behave at an oil/water interface under conditions where the composition of the aqueous phase is altered in acidity and salt concentration.  In this project we will use vibrational sum frequency spectroscopy (VSFS) and interfacial surface tension to examine two families of surfactants at the CCl4/H2O interface; sodium dioctylsulfosuccinate and sorbitan monooleate.

The REU student will conduct two kinds of experiments:  (1) VSF measurements of the vibrational spectroscopy of the dispersant at an organic/water interface, and (2) interfacial tension measurements using the pendant drop method.  The spectroscopy experiments will be conducted initially with a graduate student until he/she is familiar with the laser system and can work more independently. The project will be a valuable experience for the REU participant in combining their chemistry and physics knowledge while learning about surface science, molecular modeling, spectral analysis, laser spectroscopy, and nonlinear optics.

Nanostructured Films for Advanced Photovoltaic Materials
Steve Kevan, Physics
This project aims to develop thin film structures that will offer photovoltaic (PV) conversion efficiency beyond the so-called Shockley-Queisser limit.  Our primary near-term goal is to demonstrate that we can capture part of the excess energy of hot carriers produced by energetic photons using a process called heterojunction assisted impact ionization; this excess energy is normally lost as waste heat.  Key aspects of this project in our lab include 1) growing thin film heterostructures and nanostructured thin films that combine narrow and wide gap semiconductors, 2) measuring of the morphology and electronic structure of these films, and 3) determining the quantum efficiency and carrier decay mechanisms of these films as a function of incident photon energy through the visible regime.
 
Depending on interests, an REU student could become involved in any of these aspects.  A good example is offered for the growth by thermal evaporation and self assembly of ZnSe nanoclusters on a silicon substrate.  The student would also learn techniques such as scanned-probed microscopy, photoelectron spectroscopy, and rf photoconductivity.

Ionic Junctions of Solar Energy Conversion
Mark Lonergan, Chemistry
Traditional photovoltaics rely on an asymmetry in electronic structure or electronic carrier type for selective carrier collection and the  conversion of solar radiation into electricity.  We are exploring the   use of an asymmetry in ionic content in mixed ionic/electronic conducting polymers as a means for generating a photovoltaic effect.   The asymmetry in ionic content also leads to redox chemistry making   possible new hybrid battery/photovoltaic concepts for both energy conversion and storage.   
Students working on this project will be involved in the synthesis of ionically functionalized conjugated polymers and their detailed electrochemical characterization.  They will also be involved in the fabrication of multilayer polymer structures and their structural and electrochemical characterization.   A primary goal will be the fundamental understanding of mixed ionic/electronic conducting interfaces that use sunlight to directly drive redox disproportionation as a means of energy storage.

Coarse-graining and Multiscale Modeling Applications to the Study of Polymer Solar Cells
Marina Guenza, Chemistry
Polymer solar cells are an inexpensive alternative to silicon solar cells and have a significant industrial potential because of the light weight, mechanical flexibility, and potential for low-cost production. Current challenges in polymer solar cell research include improving performance at elevated temperatures (thermal stability) and increasing power-conversion efficiency with respect to inorganic solar cells.  
 
A key step to improve thermal stability and efficiency of polymer solar cells is to develop a deeper understanding of the microscopic mechanisms that lead polymeric materials used in solar cells to perform the way they do. For example, it has been demonstrated that improvements in power-conversion efficiency and thermal stability can be accomplished by applying post-production annealing at elevated temperatures for 30 minutes (1). The improved performance is attributed to the formation of crystalline, ordered, regions in the semiconductor polymer formed during annealing, while avoiding phase separation of the two components. It is evident that the solar cell performance is highly sensitive to the thermal and mechanical history of the polymer systems involved.

 To study morphology and thermal history of semiconductor polymers used in solar cells it is useful to perform computer simulation studies of these model systems. Data from simulations will stimulate new theoretical statistical mechanics models. Because the challenge in simulating polymeric systems for solar cells is to be able to cover the large range of length scales that are relevant for the photoconversion process, it is important to develop computational methods that allow one to do so. In Guenza’s group we have proposed novel coarse-graining methods and multiscale modeling procedures for polymeric systems that efficiently extend the range of time- and length-scales that can be investigated in molecular dynamic simulations (2-5).

The current REU project aims at extending these methods to specific polymeric systems useful for photovoltaic solar cells. The ultimate goal is to understand how to control the morphology of the system on the nanoscale as a function of the polymeric structures, mixture composition, and thermodynamic conditions. The REU student involved in this project will work closely with Chemistry and Physics graduate students to develop new theoretical approaches for coarse-graining and multiscale modeling starting from non-equilibrium statistical mechanics and liquid state theory. The student will also assist with computer simulations of polymeric systems for photovoltaic solar cells.

Interdiffusion and Nucleation at the Interface of Reacting Solids
Dave Johnson, Chemistry
By using elementally modulated reactants in which composition can be controlled on an �ngstrom length scale, we have been able to use slow solid state diffusion rates as a synthetic advantage. Controlled crystallization of elementally modulated reactants results in the rational synthesis of targeted compounds. There are several projects for REU students. These include preparing new thermoelectric materials and measuring their properties, preparing new extended cluster compounds, and preparing crystalline superlattices containing interwoven layers of different compounds. All of these projects involve preparing thermodynamically unstable compounds which cannot be prepared using conventional synthesis techniques. Although the compounds are thermodynamically unstable, they are kinetically stable. The structure of the superlattice compounds is controlled by the structure of the initial modulated elemental reactant. The rational synthesis of superlattice compounds permits the tailoring of physical properties as a function of compositional layer thicknesses and native properties of the parent compounds. The structure of the resulting products is characterized using transmission electron microscopy and x-ray diffraction. The student will measure the properties of the compounds he/she prepares, using electrical conductivity, Seebeck coefficients, Hall measurements and thermal conductivity measurements to correlate properties with structure and composition. We have had an excellent track record (in publications alone) in involving both undergraduate physics and chemistry majors in projects like these and we anticipate that this will continue in the future.

Greener Synthesis of Functionalized Inorganic Nanoparticles
Jim Hutchison, Chemistry
During the synthesis of functionalized nanoparticles, hundreds to thousands of atoms assemble into the desired structure in, typically, a rapid series of reaction steps.  Little is known about the mechanisms of these reactions and, as a consequence, syntheses are inefficient and often involve the use of highly reactive hazardous reagents. As nanotechnology moves away from demonstration to application, greener approaches to producing these materials will be essential to protecting the environment and providing benefit to society.  Given the projected broad application of nanotechnology, greening the production of nanoparticles is an important challenge for green chemistry.

New Catalyst for Environmentally Designed Ammonia
David Tyler, Chemistry
The Haber-Bosch process for the production of ammonia from N2 and H2 was arguably the most important invention of the twentieth century.  Approximately 108 tons of industrial ammonia are produced annually, and the fertilizer synthesized from this ammonia is responsible for feeding over 40% of the world’s population.  (This amount is predicted to rise to 60% by 2050.)  Temperatures of 350-550 °C and pressures in the range of 150-350 atm are required for industrial nitrogen fixation.  Such drastic reaction conditions, combined with the energy required to produce H2, account for ~1-2% of the total annual global energy consumption and for the output of greater than 3.3 ´ 108 M tons/yr of CO2 (7.3% of the worldwide total).  Due to the high energy input and high CO2 output, finding a more environmentally benign process to fix N2 is one of the grand challenges in green chemistry.  We recently reported the first example of the room temperature, atmospheric pressure reduction of N2 to NH3 using H2 as the reductant.  The reaction uses water-soluble Fe-phosphine complexes of the type Fe(P2)2Cl2 to assist in the reaction, where P2 represents a water-soluble bidentate phosphine ligand.  Our goals are to understand the mechanism of the reaction and to make the process catalytic. 

Correlation of Defect Properties of Thin Film Semiconducting Materials with Photovoltaic Performance
Dave Cohen, Physics
The research in David Cohen's laboratory is focused on trying to obtain a detailed understanding of the electronic properties of disordered semiconductors.  All such materials currently under study are of interest in the development of inexpensive thin film photovoltaic devices (solar cells).  Specific semiconducting materials we are currently studying include amorphous silicon (a-Si:H), the amorphous silicon-germanium alloys (a-Si,Ge:H), nanocrystalline silicon, and copper indium diselenide (CuInSe2 or “CIS”).  While all of these semiconductors are already being successfully incorporated in commercial solar modules, the basic mechanisms that limit their efficiencies are poorly understood.  Progress in these technologies requires a better understanding of the defect physics that may be inhibiting the collection of the photo-generated carriers within these solar cell devices.
The undergraduate student will make measurements on solar cell devices and then utilize computer modeling to deduce the influence of electronically active defects within the cell’s active semiconducting layer on its resultant efficiency.  One straightforward measurement will be to examine the current-voltage curves of the solar cell under illumination as a function of temperature.  Another method will be to look at the frequency response of the solar cell current when a small oscillating component is added to an applied dc bias across the cell.  Such results will then be examined in computer modeling programs to try to deduce the presence of electronically active defects within the semiconducting layer.   Any clear correlations that can be established between materials properties and cell performance would enable this summer project to become an important component of a valuable, publishable work.

Optical Metrology with Quantum Entangled Light
Michael Raymer, Physics
The past decade has seen advances in techniques for manipulating and measuring physical objects at the quantum level, opening a new avenue for research – Quantum Metrology. This includes quantum imaging, frequency standards, and precision time measurements. New quantum techniques offer promise for increased sensitivity and resolution. This REU project focuses on using intrinsically quantum states of light for ultrafast spectroscopy and imaging of macromolecules and other systems including biological and photosynthetic ones relating to light harvesting. Two-photon entangled states have the potential to provide simultaneous time and frequency information beyond the usual uncertainty limits, to provide enhanced microscopic spatial resolution without the deleterious effects of photo-bleaching, and to excite molecules or semiconductors along certain pathways with enhanced control. The REU student may work with diode or titanium-sapphire lasers, single-photon detectors, optical fibers, interferometers, nonlinear optics, and computer interfacing.

Multiscale Thin Metal Films for Enhanced Sensing and Light Harvesting Applications – Energy Transfer and Charge Transport Studies
Miriam Deutsch, Physics
Research interests in the Deutsch Group involve understanding the fundamental optical and electronic properties of metals exhibiting structure on a hierarchy of length scales, ranging from several nanometers to optical (micrometer) scales. Metal films with multi-scale structural roughness have been gaining newfound interest in recent years with applications that include substrates with plasmon-mediated nonlinear optical response for sensing applications and increasing solar cell efficiencies using highly scattering thin metal films. Research efforts are currently addressing energy transfer (optical excitations) and charge transport through chemically deposited thin silver films. Better understanding of energetic processes in these materials will allow optimization of their use as targeted sensors for biological or chemical contaminants, as well as their implementation in efficient light harvesting devices.

Molecular Orientation and Two-dimensional Mobility of Polymerice Glycoprotein Mimics
Raghuveer Parthasarathy, Physics
Our group explores the physical properties of biological membranes. One area involves the mechanisms that control the structure, orientation, and mobility of large cell-surface proteins, specifically brush-like "mucins" believed to jut out from cellular membranes.
An REU student in our lab would work on incorporating newly developed synthetic analogs of mucins into lipid membranes and using powerful interferometric imaging techniques to examine the nanometer-scale structure and dynamics of the resulting materials. The student will become familiar with sample preparation, optics and microscopy, and computational data analysis in the course of examining a unique class of materials.

Phenyl-Acetylene Scaffolding as Optoelectric Materials
Michael Haley, Chemistry
Research efforts in the Haley laboratory revolve around the assembly of functional molecules comprised of benzene and acetylene building blocks. Their construction is based extensively on established synthetic methods as well as on reaction sequences developed and/or modified in our lab. These advances allow us to assemble a variety of structures that are of a discreet size and of a desired substitution pattern.  One avenue of our phenylacetylene research seeks to address fundamental problems in the development of the next generation of molecular probes and binding agents for anions. Anions are problematic environmental contaminants and are vital to many processes in nature, with anion binding proteins and transport channels implicated in the mechanisms of many disease pathways. Therefore, understanding anion binding on a molecular level, in particular new anion binding motifs and anion-directed self-assembly, is of importance to numerous fields of science and human health.
An REU student would help construct and study additional phenyl-acetylene scaffold receptors, thus further refining their design for optimal anion binding. A small set of new receptor targets would first be identified and then prepared. Given that our syntheses are modular (think molecular level Legos or Tinkertoys), most of the starting materials are readily available; thus, construction of the compounds would be straightforward. The student would characterize the new molecules by traditional techniques (NMR, IR, UV-vis, MS) as well as more elaborate methods (fluorescence including lifetimes). Binding studies with a variety of anion targets would then be explored.

Controlling Properties of Graphene Devices through Surface Chemistry
George Nazin Chemistry
Organic semiconductors have received a great deal of attention due to their potential for fabrication of lightweight, large-area, and low-cost solar cells. One important issue for the commercial viability of organic solar cells is the cost-efficient fabrication of transparent, conducting electrodes, which are required for the light to be able to reach the active area of the cell. Currently, the materials available for fabrication of transparent electrodes are either too expensive or have suboptimal conductivities. A promising novel transparent electronic material is graphene which has exceptionally high charge carrier mobility. We are investigating the routes to chemical manipulation of graphene bandstructure, which is important for fabrication of cells with efficient collection of photo-generated charge carriers.
The undergraduate student involved in the project will participate in the studies of graphene device doping via surface chemistry methods. The student will be trained (under the guidance of a graduate student) in the following techniques: optical spectroscopic characterization of graphene, fabrication of graphene devices using e-beam lithography, vacuum-based graphene surface chemical modification, electrical characterization of the graphene devices, and investigations of the device’s internal band-structure profiles using scanning photocurrent and scanning gate microscopies.

Supramolecular Chemistry
Darren Johnson, Chemistry
The Johnson laboratory uses supramolecular chemistry as a tool to approach a variety of problems in organic, inorganic and environmental chemistry.  Research topics include i) developing a supramolecular design strategy for the specific chelation of hazardous metals such as arsenic, lead, and mercury; ii) molecular recognition of anions and biologically relevant small molecules, and iii) developing greener approaches to prepare metal oxide thin films for electronic device applications.  Students can also participate in inorganic nanocluster synthesis within our Center for Green Materials Chemistry (http://uoregon.edu/~grnchem/).
REU students would be introduced to concepts in the field of supramolecular chemistry and they will specifically apply the principles of self-assembly, molecular recognition, organic, and inorganic synthesis to prepare new molecules.  A representative project for an REU student would involve first learning the basics of computer modeling (molecular mechanics and DFT) to design a ligand capable of forming a nanoscale assembly in the presence of a specific toxic metal ion such as As3+ or Hg2+. Ligands designed from this work will selectively chelate the target toxic metal ion, enabling applications in environmental remediation and sensing of a variety of problematic environmental contaminants. The REU student would perform the organic synthesis necessary to prepare the ligand, the inorganic synthesis required to form the complex, and the characterization to prove the assembly composition (NMR spectroscopy, mass spectrometry, X-ray crystallography, etc.).  This project will give the student a working knowledge of supramolecular chemistry, expose him/her to the basics of computer modeling, and provide hands-on organic and inorganic synthesis experience.  

Inorganic Materials Chemistry for Solar Energy Conversion and Storage
Shannon Boettcher, Chemistry
The continued prosperity of our current civilization will require replacing fossil fuels with renewable, sustainable energy sources. Using sunlight, by far the largest power source on the planet, to generate portable, energy-dense fuels via a closed-loop chemical cycle is arguably the most attractive solution. The simplest cycle imaginable would involve the photo-driven splitting of water into molecular oxygen and hydrogen. The Boettcher group synthesizes and studies solid-state inorganic materials that may be useful for facilitating this process. Students working on this project will use solution-phase inorganic chemistry to synthesize oxide-based semiconductors. The relevant physical/structure properties will characterized using a variety of materials analysis techniques (x-ray diffraction, electron microscopy, x-ray photoelectron spectroscopy, etc.) and correlated to photo- and electrocatalytic behavior. 

Influence of nanoparticles on RNA structure and function
Vickie DeRose, Chemistry
As the development of nano-scale materials progresses, it is important to understand how these materials may influence the physical and chemical properties of biological macromolecules such as RNA.  RNA molecules carry a large negative electrostatic potential, attract an atmosphere of cationic counterions, and have nanoscale regions of architecture that may associate strongly with nanoparticles in a materials-dependent manner. The goals of this research are to investigate such associations and their consequences to RNA structure and function. As an initial screen for binding and structure changes, the activity of a ribozyme (catalytic RNA) will be used to monitor influences of nanoparticles on RNA.

Students working on this project will learn to perform kinetic assays for RNA reactivity based on the hammerhead ribozyme, a 65-nucleotide RNA whose activity is very sensitive to structure and cations. REU students will then investigate the influence of different nanoparticles, Ga (13) metal clusters and size- and ligand-shell-controlled Au nanoparticles on the RNA catalyst using the kinetic assay for ribozyme activity. Depending on timeframe, students will either use materials provided by the Johnson and Hutchison laboratories, or synthesize and characterize their own materials. These experiments will provide cross-training in important concepts of kinetics, biopolymer structure, handling and possibly synthesizing nanomaterials, and quantitative analysis of complex molecules.

Studies of Exciton Structure and Dynamics in Model Light Harvesting Complexes
Andy Marcus, Chemistry

The collection and redistribution of sunlight by highly ordered arrays of chromophore molecules is the primary event in photosynthesis, and plays a prominent role in many synthetic solar energy strategies. Highly efficient electronic excitation transfer (EET) from the periphery of antenna complexes to charge-carrier-generating reaction centers is a key event in these systems. Although much is known about the mechanisms of EET in multi-chromophore systems, the exact chemical principles that lead to its high efficiency in photosynthesis are not well understood. The current project aims to measure the couplings and dynamics of collective excitations (excitons) in model chromophore complexes using fluorescence-detected two-dimensional electronic coherence spectroscopy (F2D-ECS), an ultrafast laser technique well suited to this purpose and recently developed in the Marcus laboratory.

The REU student will work with a senior graduate student or postdoc to perform F2D-ECS experiments on membrane-bound porphyrin assemblies. The REU student will help to prepare lyposome samples, assist with routine laser instrumentation alignment, record experimental data, participate in data analysis, and learn theoretical concepts underlying exciton dynamics in light harvesting systems.

Developing novel Boron (B)-Nitrogen (N)-Containing Heterocycles for Applications in Renewable Energy and Sustainability
Shih-Yuan Liu, Chemistry
We are engaged in synthetic organic chemistry with emphasis on developing molecules of importance in applications related to sustainability and energy. We are especially interested in the development of B–N-containing heterocycles, namely 1,2-azaborines. These structures are isoelectronic and isostructural to the ubiquitous benzene motif. In contrast to benzene derivatives, the corresponding 1,2-azaborines have not been extensively explored. We aim to exploit the unique properties of 1,2-azaborines and investigate their potential in H-storage-, sensing-, and solar energy applications. 

Quantum Measurements and Quantum Dynamical Systems
Dan Steck, Physics
One of the most intriguing aspects of quantum mechanics remains the measurement process.  An important modern paradigm for quantum measurement is the continuous, indirect measurement of quantum systems–in our case, ultracold rubidium atoms trapped by laser light.  We are working towards realizing and better understanding continuous quantum measurements, with two main long-term goals.  First, we are working towards implementing quantum feedback control of atomic motion, which is inherently challenging due to quantum mechanics itself: to control the state of an atom, we must continuously gain information about it, but to gain the information we must also disturb them.  This is, unfortunately, contrary to our control goals of putting the atom into a desired state.  Second, we are working towards understanding the correspondence between classical and quantum mechanics, which is particularly challenging for systems that are chaotic in the classical limit.  Further, understanding continuous quantum measurements will benefit future technologies in quantum-information processing and quantum-limited, precision metrology.

The REU student in our group will work closely with me and graduate students on any of a variety of projects according to the student's interests, in support of our experiments on continuous measurements of the motion of ultracold atoms, ranging from designing and constructing electronics and laser systems to theoretical simulations.  Possible projects include: developing novel, microcontroller-based hardware for timing and control of cold-atom experiments; developing and characterizing ultrastable diode-laser systems; helping to design and set up optical detection systems to track single, trapped atoms in real time; and computational simulations of optical continuous measurements on single atoms.