Overview
Prof. Kathy Rowlen
Prof. Stephen Leone
Prof. Veronica Vaida
Prof. Margaret Tolbert
Prof. David Nesbitt
Prof. John Birks
Prof. David Jonas
Prof. Steven George
Prof. W. Carl Lineberger
Prof. Robert Kuchta
Prof. Josef Michl
Prof. Carl Koval
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Faculty Research Projects: Overview

Interfacial chemistry is enormously important in an incredibly diverse range of fields, from aerosol science to investigations of DNA replication. The "interface" itself is a broadly defined term which may include interactions between any combination of solids, liquids and gases. Research experience in interfacial chemistry is important for students interested in careers in industry, research labs, or academia. This section contains descriptions of the research interests for the 12 faculty members involved in the REU program.  They cover a diverse range topics, including: understanding the surface chemistry of atmospheric aerosols; electron transfer at liquid-liquid interfaces; investigation of the self-formation and surfactant-mediated growth of nanodots on surfaces; determination of molecular orientation at surfaces; and gas-solid reactions studied by atomic force microscopy. The faculty and projects bridge the traditional fields of analytical chemistry, physical chemistry and biochemistry.  Since the exact REU projects vary each summer, it is most important to pick a research advisor that is doing work in a field that is interesting to you.  When you list your choices in the application, you will be listing faculty advisors, not specific projects.

Rowlen Group Research Project:  Multi-channel Gel Electrophoresis on a Palm-Sized Chip

Gel electrophoresis is a tremendously important technique for the separation and sequence identification of DNA.  However, currently employed technology is tedious and time-consuming.  A new gel electrophoresis device has been developed that provides all of the benefits of the new microfluidic approach to electrophoresis with none of the disadvantages.  Parallel channels (2 mm wide x 4 mm deep) are machined in plastic.  The reusable device is therefore inexpensive, lightweight and can be used with existing gel imaging technologies, such as a trans-illuminator.  The channels allow for easy gel and sample loading, fast gel time, and rapid heat dissipation during an electrophoretic run.  The preparation time for a typical agarose gel within the channels is a fraction of that required for a slab gel.  Complete separation of a standard DNA ladder (FX-174-RF, see Figure below) within agarose-filled channels can be achieved within 15 minutes.  Separation of the components in FX-174-RF within a slab gel requires a minimum of 40 minutes.  We would like to optimize the system in order to achieve separations within 2 minutes - comparable to similar separations demonstrated within microfluidic devices.

This project is designed for an undergraduate to work independently.  The project would involve optimization of both physical and experimental parameters to achieve rapid separation of DNA.  In addition, we are interested in extending this technology for the separation of proteins using polyacrylamide gels.

The figure on the left is the channel gel electrophoresis device.  It is the size of a handheld HP calculator.  The figure on the right is a digital image of fluorescently stained a DNA (FX-174-RF) ladder separated within agarose filled channels.

Additional Information on the Rowlen Group

Leone Group Research Project:. The self-assembled growth of nanoscale materials is sensitively dependent on the kinetic rates of formation and diffusion of materials, as well as thermodynamic stability and strain energies. In this project, an undergraduate student will be introduced to the self-formation and surfactant-mediated growth of nanodots of a material such as germanium on silicon (100) single crystals. New research involves the effect of a fractional layer of a surfactant material such as As or Sb on the dot growth and formation. The surfactant changes the diffusion length of the Ge atoms on silicon and lowers the free energy of the surface layer, making it easier for the Ge to grow either layer-by-layer or to form smaller, nanodot-sized islands. The studies will investigate the kinetics of the growth and the dot size as a function of surfactant density, deposition rate, and substrate temperature. A molecular beam epitaxy system is used for the deposition and an atomic force microscope is used for the analysis of the dot size distribution. The results are expected to obtain new information about the kinetic and thermodynamic manipulation of epitaxial growth. A previous undergraduate, John Bright, initiated this project and brought it to a successful point, together with a postdoctoral associate.

Facilities/Instrumentation Associated with the Project: Atomic force microscope, Ultrahigh vacuum molecular beam epitaxy deposition system/ion pumps, titanium sublimator, gauges, sample manipulator, Quartz microbalance, Reflection high energy electron diffraction spectrometer, Single crystal sample preparation equipment, Laser ionization time-of-flight mass spectrometer, Effusion sources of atomic beams

Additional information on the Leone Group

Vaida Group Research Project: The chemical and optical properties of atmospheric aerosols have been shown to be important in tropospheric oxidation, urban pollution, health, atmospheric radiative transfer and climate. To add to this interesting problem, recent field measurements have shown that tropospheric aerosols have an unexpectedly large organic content, which will further modify the optical properties of aerosols and their role in absorption of solar radiation and the Earth climate. We recently proposed a structural and chemical model for tropospheric organic aerosols which predicts an inverted micelle structure for nascent organic aerosols with a hydrophilic core and a hydrophobic organic coating. We predict the chemistry involving atmospheric radicals, which will process the organic layer. Laboratory spectroscopic experiments are designed to probe the effect of radical reactions on the hydrophobic interfacial film. An undergraduate student, working under the supervision of a postdoctoral fellow, would perform ultraviolet and visible spectroscopic experiments of organic films on NaCl substrates before and after processing of these films by Cl, O₃ and OH. The results will be input to atmospheric models to establish the impact of these radical reactions. The student will learn the basis of spectroscopic measurements as well as data interpretation and atmospheric modeling.

Facilities/Instrumentation Associated with the Project: UV/Vis Spectrometer, light sources, detectors, microwave discharges, Nd/Yag laser, computing.

Additional information on Vaida's Research

Tolbert Group Research Project: It is now well established that heterogeneous chemistry on stratospheric aerosols plays a key role in the decadal ozone losses observed over the poles and around the world. While less is known about tropospheric aerosols, it is likely that heterogeneous reactions on these particles are important for tropospheric chemistry. In addition, tropospheric particles play an important role in global climate and can be a serious threat to human health. One key uncertainty in assessing the role of atmospheric aerosols is a lack of knowledge about aerosol phase in the atmosphere. We would like to involve an undergraduate research assistant in performing laboratory experiments to determine the phase of well-defined aerosols systems. The proposed studies would be a follow-on to a previous undergraduate research project performed by Megan Wilson (who graduated Summa Cum Laude with her undergraduate thesis). Megan measured the low-temperature deliquescence and efflorescence of pure ammonium sulfate aerosols under atmospheric conditions. However, since recent data is showing that almost all tropospheric particles are mixtures, it would be highly desirable to measure the low temperature deliquescence and efflorescence of mixed aerosol particles. Initial studies will be performed on mixtures of sulfates with organics. As in the previous work, the aerosol phase changes will be measured in a low- temperature flow tube equipped with FTIR spectroscopic detection of the aerosols.

Facilities/Instrumentation Associated with the Project: FTIR spectroscopy, vacuum techniques, flow tube techniques, aerosol generation techniques, frost-point hygrometer, low-temperature chemistry, phase diagrams

 Additional information on the Tolbert Group

Nesbitt Group Research Project: The use of lasers and ultrasensitive light detection methods now permit the study of fundamental physical, chemical and photochemical reactions at an unprecedented level of detail. In the Nesbitt labs, there are laser-based projects in three different areas related to atmospheric and interfacial chemistry that would be suitable for undergraduate research training and participation. 1) Atmospheric chemistry: Pulsed lasers are used to photolytically generate highly reactive atmospheric radicals (e.g.. OH, HO₂) in a temperature controlled flow cell, with the concentrations of these radicals monitored as a function of time by either direct IR laser absorption or laser induced fluorescence methods. This thereby allows chemical reactions to be studied under controlled laboratory conditions at temperatures relevant from the stratosphere to troposphere. 2) Cavity ringdown laser spectroscopy: Ringdown times for tunable pulsed laser light injected into optical cavities with high reflectivity mirrors (99.999%) are used to investigate ultrasensitive absorption spectroscopy of trace species (in absorption path lengths corresponding to many kilometers. In conjunction with a slit discharge supersonic expansion, this capability permits spectroscopic characterization of highly reactive radicals and molecular ions under jet cooled (20K) temperatures. 3) Single molecule spectroscopy: In conjunction with ultrasensitive avalanche photodiode detectors, laser excitation in a confocal microscope apparatus can be used to study the kinetics and photophysics of single molecules (dyes, semiconductor nanocrystals, fluorescent proteins). A CCD array detector will be used with this confocal apparatus to image fluorescently labeled DNA strands for studies of electrophoresis at the single molecule level.

Facilities/Instrumentation Associated with the Project: Single mode Ar⁺, Kr⁺, and cw dye lasers, excimer lasers, F-center laser, IR detectors, Nd:YAG pumped dye laser, confocal microscope, avalanche photodiode detectors, ellipsometer, stereo microscope, fluorimeter, Nd/Yag laser, dye laser, photomultiplier tube detetectors, charge coupled device detectors

Additional information on Nesbitt's Research

Birks Group Project: The detailed mechanism of the gas-solid reactions of ozone with carbonaceous nanoparticles such as nanocrystals of polyaromatic hydrocarbons and buckminsterfullerene (C₆₀), carbon nanotubes, graphite and n-hexane soot will be studied using the technique of atomic force microscopy. The materials all contain sp²-hybridized carbon but differ in strain energy and the presence of crystalline edges. The long-term goal is to obtain a quantitative understanding of the rate of reaction of soot particles with ozone in the atmosphere. Soot aerosols, which are introduced to the atmosphere by combustion sources, may contribute significantly to global warming by absorbing sunlight. The reaction of soot with ozone could also affect ozone concentrations and thereby increase the amount of ultraviolet radiation reaching the Earth’s surface. The reaction of ozone with soot produces volatile products (CO, CO₂ and H₂O); thus, the collisional reaction efficiency in each dimension of the particle can be measured by following the rate of particle shrinking in that dimension. For example, preliminary work has shown that anthracene nanocrystals react exclusively at the crystal edges, removing vertical layers one at a time. This new approach will allow a detailed study of the mechanism of reaction of ozone with carbonaceous particles at very near the molecular level for the first time.

Facilities/Instrumenation Associated with the Project: atomic force microscope equipped with environmental chamber; ozonator; diode array spectrometer; ozone, water vapor, pressure and temperature sensors

Additional information on the Birks Group

Jonas Group Project: The research opportunities for undergraduates in our group include studies of vibrational and solvent motions in liquids on a femtosecond timescale, electronic coupling between chromophores in aggregates, energy transfer in photosynthesis, and chemical reactions in solution. Many of these problems involve the study of interfacial forces, solvation, and solvent restructuring around excited species, all of which occur at the interface in solvation effects. Our projects typically involve both investigations of linear absorption and emission spectroscopy suitable for undergraduates to carry out primarily on their own and femtosecond experiments in which close collaboration with graduate students is essential during all phases of the experimental work and subsequent data analysis. Some of the femtosecond investigations involve the technique of two- dimensional Fourier transform electronic spectroscopy (analogous to 2D NMR) first demonstrated by our group. This technique essentially reveals the dynamics of individual molecular environments on a femtosecond time scale and may be a powerful complement to single molecule spectroscopy.

Facilities/Instrumenation Associated with the Project: The available equipment includes a cavity dumped femtosecond laser system, an amplified femtosecond laser system, two multiple beam interferometers with computer controlled delay stages, two spectrometers, a CCD array, signal detection electronics, and computers for data collection and analysis.

Additional information on Jonas' Research

George Group Project: The George research group focuses on topics in surface chemistry, thin film growth and heterogeneous atmospheric chemistry. The two main areas currently under investigation are atomic layer controlled thin film growth and kinetic processes in ice. Both of these areas are available for undergraduate research participation with guidance from a graduate student. In our work on atomic layer deposition, we have developed surface reaction sequences that control growth at the atomic level. This strategy is based on self-limiting surface chemistry. We study the surface chemistry in a vacuum chamber using Fourier transform infrared (FTIR) spectroscopy. The thin film growth is monitored in another vacuum chamber using spectroscopic ellipsometry. Our current work is using the atomic layer controlled growth method to deposit nanolaminates. Nanolaminates are multilayer structures where the layers change composition every ~20-50 Angstoms. Nanolaminates may have very different thermal, electrical and mechanical properties than their individual components. Ice is probably the most important molecular solid on earth. Ice over the poles contains a record of the Earth's atmosphere over the last 100,000 years. Ice also plays an important role in atmosphere. In a third vacuum chamber, we are currently measuring adsorption and diffusion kinetics in ice using laser resonant desorption and mass spectrometric detection techniques. An Er:YAG laser that emits light at 2.94 microns is employed to excite resonantly the O-H stretching vibration in H2O. The excitation is converted to heat and leads to the desorption of H2O from the ice film. By using sequential laser pulses, we can literally dig down into ice to determine how far molecules have diffused into the ice.

Facilities/Instrumentation Associated with the Project: Fourier transform infrared (FTIR) spectrometer, in situ ellipsometer, Q-switched Er:YAG laser, associated vacuum chambers and quadrupole mass spectrometers.

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Lineberger Group Research Project:Photoelectron spectroscopy provides a very rewarding way for undergraduates to become involved in physical chemistry research. The fundamental concepts of the experiments are already known to the student, but there is ample opportunity to learn new technologies, carry out quantum chemical calculations, and, most important, to discover the thrill of being the first person to measure something. The anion photoelectron spectroscopy experiments employed in our group are sufficiently uncommon that it is possible to select small anions that are virtually unstudied. A typical project is to obtain and analyze the photoelectron spectrum of a diatomic anion, whose state might play a larger role in thin film materials, and publish a short note describing the results in a journal such as the Journal of Chemical Physics or the Journal of Physical Chemistry. In the process of carrying out this project, the students will also introduced to data-base literature searches and to various bibliographic systems. As an example project, two undergraduates from Stockholm University are currently obtaining and analyzing the photoelectron spectrum of Cu₂O- , with the objective to see if they can understand differences between Cu₂O and Ag₂O that might be important for high temperature superconductivity. Such projects invariably generate a real excitement for chemistry. Even more important, however, is that the research experience gives students a much greater appreciation of the real nature of research.

Facilities/Instrumentation Associated with the Project: Lasers, sophisticated optical instrumentation, mass spectrometers.

Additional information on the Lineberger Group

Kuchta Group Research Project: We are interested in understanding the structural organization of DNA polymerase a- primase. This enzyme complex contains 4 subunits, and is essential for nuclear DNA replication. Presently, there is no information on the structure of either the complex or any of the individual subunits. To understand how the 4 subunits are organized, we will use atomic force microscopy to examine DNA polymerase a- primase. The protein(s) will be bound to a mica surface and examined under solution. Importantly, we have already developed methods to immobilize the polymerase a-primase complex on the mica surface by taking advantage of polymerase a’s high affinity for DNA, and then image the DNA-protein complexes by atomic force microscopy. Using these methods we have already established, an undergraduate will examine various DNA polymerase a-primase complexes bound to DNA using atomic force microscopy. With direct guidance from a graduate student, the undergraduate will compare the structure of the 4 subunit polymerase a-primase complex with complexes lacking 1-3 subunits. In addition to learning about atomic force microscopy and structure analysis, the student will learn about protein expression, purification, and measurement of enzyme activity.

Facilities/Instrumentation Associated with the Project: Atomic force microscopes, centrifuge, gel electrophoresis apparatus, incubators, phosphorimager, scintillation counters, tissue culture hood, ultracentrifuge, .

Additional information on Kuchta's Research

Michl group project: The synthesis of a sturdy, large and regular planar square grid polymer by linear coupling of cross-shaped monomers confined to a liquid surface is an attractive target for fundamental reasons (investigation of molecular dipolar rotors mounted at the nodal points of the grid, currently funded by the NSF), as well as for practical applications such as size-based separations (currently funded by the USARO). The Michl group has developed procedures that have so far led to polymer molecules that were either regular and large (many microns across) but fragile (monomer-to-monomer connections were reversible, e.g., hydrogen bonds) or sturdy but irregular and relatively small (fraction of micron across, with covalent connections). The proposed project will represent an attempt to combine the best of both sets of properties by doing reversible assembly into a large regular square grid polymer molecules first, followed by gradual exchange of the weakly bound reversible couplers for sturdy covalent couplers). The undergraduate student will be assigned a particular monomer structure and a particular coupler structure to test and will work closely with an experienced post-doctoral fellow thoroughly familiar with all the procedures and equipment.

Facilities/Instrumentation Associated with the Project: The project will involve work with instruments such as a Langmuir-Blodgett trough, AFM-STM, FT-IR, Raman, and an ellipsometer, all of which are presently available in the laboratory.

Additional information on the Michl Group

 Koval Group Research Project: Electron transfer reactions (ETRs) are one of the major classes of chemical reactions. As the result of numerous experimental and theoretical studies, much is known about certain types of ETRs such as within molecules, between two molecules in solution, and between molecules in solution and conducting solids. A type of ETR that has been studied far less extensively are reactions between molecules at liquid-liquid interfaces (LLIs). Further understanding of ETRs at LLIs is important due to their role in biological processes and to their potential utility in industrial processes.

In order to provide experimental data that is critical for the evaluation and development of theoretical models describing ETRs at LLIs, we propose to measure rate constants for a carefully chosen series of reactions. Hydrophillic Ru(III,II) and Fe(III,II) ammine and aquo complexes will be reacted with hydrophobic organo-metallic Fe(III,II) couples. The same reactions will be studied at three water/organic solvent LLIs that vary in dielectric properties and in the structure of the interface itself. The rate constants will be measured utilizing carbon electrodes coated with thin films of organic solvents placed in electrochemical cells containing aqueous solutions. Equilibrium constants will be measured for the ETRs at LLIs as will the partition coefficients for the various reactants and products.

Facilities/Instrumentation Associated with the Project: electrochemical instrumentation including: computer driven potentiostat/data processor, potentiostat/coulometer, universal programmer, bipotentiostat with RRDE rotator, recorders; helium-filled glove box;vacuum line, rotary evaporator, centrifuge; diode-array spectrophotometer; possibly departmental NMR and mass spectrometry facilities.

Additional information on Koval's Research

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