J. Douglas McDonald
Emeritus Professor of Chemistry
Professor J. Douglas McDonald attended Rice University where he received his B.A. degree in 1966. He received his Ph.D. from Harvard in 1971, at which time he joined the faculty at the University of Illinois. His research interests are in physical chemistry and chemical physics. The first observation of vibrational-electronic quantum beats was made in his laboratory.
Recent technological advances have made it possible to study the behavior of single molecules ranging from single, small dye molecules to large biopolymers such as DNA and proteins. Our research uses two general methods for this work: Atomic Force Microscopy (AFM) and optical studies such as fluorescence lifetime measurements, fluorescence energy transfer, and surface-enhanced Raman. We have developed an apparatus to use AFM and optical studies simultaneously on a molecule tethered to a glass surface.
Protein Folding. Conventional protein folding kinetics studies look at large ensembles of individual molecules and see only the average path taken by all molecules, thus detecting only bottlenecks that every molecule must pass. However, theories predict that individual molecules can fall into many different "trap" states that exist only briefly, yet substantially slow the overall process. We propose to mount a single protein molecule on glass with a tether containing a stable dye molecule, then to attach a different dye to a remote place on the protein. Fluorescence energy transfer between the dyes will monitor the distance between them as the molecule folds.
Materials Studies. We have developed techniques for studying single molecules for materials applications, obtaining optical images of single dye molecules with spatial resolution of 20 nmmore than ten times smaller than the diffraction limit of light. We plan to extend this method by observing the entire Raman spectrum of single molecules with this resolution. Our techniques can be used to study both inorganic and biological molecules.
Nanolithography. A third field
we are pursuing is nanolithography using AFM tips to write on transparent
glass substrates coated with organic thin films. We use Pd-coated
AFM tips to catalytically attach reactive amine groups to otherwise
inert surfaces. We recently achieved record contrast ratios for
writing on organic monolayers, with a density ratio of reactive
groups in written versus unwritten areas of over ten million.
"Nanoscale Site-Selective Catalysis of Surface Assemblies by Palladium-Coated Atomic Force Microscopy Tips: Chemical Lithography without Electrical Current," C. Blackledge, D. A. Engebretson and J. D. McDonald, Langmuir, 16, 8317 (2000).
"Catalytic Activity of Silanols on Carbamate- Functionalized Surface Assemblies: Mono-alkoxy versus Trialkoxy Silanes," C. Black-ledge and J. D. McDonald, Langmuir, 15, 8119 (1999).
"Picosecond Real Time Study of the Bimolecular Reaction O(3P)+C2H4 and the Unimolecular Photodissociation of CH3CHO and H2CO", Osama Abou-Zied and J. D. McDonald, J. Chem. Phys., 109, 1293-1301 (1998).
"Real Time Study of Bimolecular Interactions Direct Detection of Internal Conversion Involving Br(2P1/2) + I2 Initiated From a van der Waals Dimer," M. F. Tuchler, S. Wright, and J. D. McDonald, J. Chem Phys., 106, 2634, (1997).
"Multiphoton Ionization Spectroscopy of Hydrogen Iodide," S. A. Wright and J. D. McDonald, J. Chem. Phys., 101, 238, (1994).