|
Activities & Awards
Distinguished Teaching Award in Chemistry,
University of Utah, 1978
David
P. Gardner Faculty Fellow, 1981
Alfred P. Sloan Fellow, 1985-1989
Coblentz Memorial Prize in Molecular Spectroscopy, 1986
University of Utah Distinguished Research Award, 1988
ACS Division of Analytical Chemistry Award in Chemical Instrumentation,
1991
Pittsburgh Analytical Award, 1999
Editor-In-Chief, Applied Spectroscopy, 1998-present
Research Interests
Our research involves the application of lasers in chemical analysis,
in the spectroscopy of colloids, and in studies of liquid/solid interfaces.
Many new chemical materials and processes depend on the dispersion of
small particles in liquids. Probing the chemistry of colloids
represents a significant challenge for chemical analysis. Due to the high
specific surface area of these materials, their physical and chemical
properties are dominated by structure and dynamics at their surfaces;
thus, meaningful analytical measurements must be selective for the particle
surface/solution interface. Transport of molecules to and from the material
surface is influenced by particle aggregation and organization on nm to
µm distance scales, requiring measurements that are informative of nanoscale
structure. The relation-ship between colloidal materials and analytical
chemistry is not confined to measurement challenges since these materials
also provide unique support structures for new methods of chemical detection
and analysis.
Our program addresses both the measurement challenges and new opportunities
for chemical analysis using colloidal materials: 1) Time-resolved luminescence
spectroscopy is used to probe molecular transport and surface reactions
at the single-molecule level. 2) Vibrational spectroscopy methods,
both Raman scattering and infrared absorption, are being adapted to observing
interfacial reactions in colloidal dispersions and in porous solids. 3)
Single-molecule detection methods are used to report distributions of
particle sizes, aggregation, and chemical composition. Optical-trapping
provides long residence times to observe Raman scattering from individual
colloidal particles to monitor chemistry in these nanoscale structures.
A second major research effort of our group is to develop spectroscopic
methods for exploring molecular structure and dynamics at interfaces between
dielectric solids and liquids. These new spectroscopic and kinetic tools
lead to understanding the interfacial chemistry that impacts analytical
methods (chromatography, solid-phase extraction, metal-ion complexation,
and optical sensors) and environmental transport and clean up (adsorption
and transport kinetics). We have been developing in situ vibrational spectroscopies, both Raman
and infrared, to probe the chemical structure of adsorbed and bound species
at silica/solution interfaces.
|
|
We are using these tools to investigate
metal-ion complexation at silica-immobilized ligands, the mechanisms and
rates of binding siloxane ligands to silica surfaces, and the specific
molecular interaction responsible for adsorption, solid-phase extraction,
and molecular recognition at chemically-modified silica surfaces. Surface-enhanced
Raman spectroscopy at the surface is being adapted to fast relaxation
kinetic measurements through the use of electric-field perturbations.
Selected Publications
- "Optically-Trapping of Unilamellar Phospholipid Vesicles: Investigation of the Effect of Optical Forces on the Lipid Membrane Shape by Confocal-Raman Microscopy", Daniel P. Cherney, Travis E. Bridges, and Joel M. Harris, Analytical Chemistry (Accelerated Article),
76
, in press (2004).
- "Potential-Dependent Surface-Enhanced Raman Scattering from Adsorbed Thiocyanate for Characterizing Silver Surfaces with Improved Reproducibility", Vanessa Oklejas and Joel M. Harris, Applied Spectroscopy,
58
, in press (2004).
- "Resolution of Intermediate Adsorbate Structures in the Potential-dependent Self Assembly of n-Hexanethiolate on Silver by In-Situ Surface-Enhanced Raman Spectroscopy", Rory H. Uibel and Joel M. Harris, Applied Spectroscopy,
58
, in press (2004).
- "Polyamidoamine Dendrimers as Nanoscale Diffusion Probes in Sol-Gel Films Investigated by Total-Internal-Reflection Fluorescence Spectroscopy", Karla S. McCain, Peter Schluesche, and Joel M. Harris, Analytical Chemistry,
76, 939 (2004).
- "Modifying the Adsorption Behavior of Polyamidoamine Dendrimers at Silica Surfaces Investigated by Total-Internal-Reflection Fluorescence Correlation Spectroscopy", Karla S. McCain, Peter Schluesche, and Joel M. Harris, Analytical Chemistry,
76, 930 (2004).
- "Spatially-resolved Analysis of Small Particles by Confocal Raman Microscopy: Depth Profiling and Optical Trapping", Travis E. Bridges, Michael P. Houlne, and Joel M. Harris, Analytical Chemistry,
76, 576 (2004).
- "Optical-Trapping Raman Microscopy Detection of Single UnilamellarLipid Vesicles", Daniel P. Cherney, John C. Conboy, and Joel M. Harris, Analytical Chemistry,
75, 6621 (2003).
- "Spectroscopic studies of Proton-transfer and metal-ion binding of a solution-phase model for silica-immobilized 8-hydroxyquinoline", Rory H. Uibel and Joel M. Harris, Analytica Chimica Acta,
494
, 105 (2003).
- "Single-molecule Fluorescence Trajectories for Investigating Molecular Transport in Thin Silica Sol-gel Films", Karla S. McCain, David C. Hanley and Joel M. Harris, Analytical Chemistry (Accelerated Article), 75, 4351 (2003).
- "SERS-Based Vibrational Stark Effect as a Spatial Probe of Interfacial Electric Fields in the Diffuse Double-Layer", Vanessa Oklejas, Christopher Sjostrom, and Joel M. Harris, Journal of Physical Chemistry, B,
107, 7788 (2003).
- "In-Situ Investigation of Binary-Component Self-Assembled Monolayers: A SERS-Based Spectroelectrochemical Study of the Effects of Monolayer Composition on Interfacial Structure", Vanessa Oklejas and Joel M. Harris, Langmuir,
19, 5794 (2003).
- "Total-Internal-Reflection Fluorescence-Correlation Spectroscopy Study of Molecular Transport in Thin Sol-Gel Films", Karla S. McCain and Joel M. Harris, Analytical Chemistry, 75, 3616 (2003).
|
