Alan Van Orden Professor

Office: Chemistry C207

Phone: (970) 491-6286


  • Ph.D., University of California at Berkeley


Our research contributes to both the fundamental and applied aspects of single molecule spectroscopy. One area of current interest is in studying the spectroscopic properties of individual fluorescent dye molecules that have been used to label specific sites of biological macromolecules. These studies provide us with insight into the chemical environment of the dye and allow us to observe subtle differences in these properties from molecule to molecule. By simultaneously recording atomic force microscope images, we can directly probe the relationship between the spectroscopic properties of the dye and the structures of the biomolecules. Another major emphasis of our research is in the development of new analytical instruments that combine the speed and sensitivity of single molecule spectroscopy with the selectivity of electrophoresis. A variety of techniques are used to determine the electrophoretic mobilities of single molecules in microcapillaries or in gel matrices, including fluorescence correlation spectroscopy and single molecule tracking microscopy. Because of their different electrophoretic mobilities, the components of a mixture can be analyzed without the need to perform a chemical separation. More rapid and efficient methods for characterizing the interactions between small molecules, such as drugs or environmental toxins, and biological molecules, like nucleic acids, peptides, and proteins, are being developed in this way. Experimental techniques that are utilized in our research include steady-state and time-resolved laser spectroscopy, optical and atomic force microscopy, chemical synthesis, and molecular biology. The research is multidisciplinary in nature, and students who participate in these projects gain a broad background in the analytical, physical, biological, and environmental sciences. The ability to detect and characterize individual molecules using spectroscopic methods has opened the door to many new possibilities in the analytical, physical, and biomolecular sciences. For example, much of what we know about chemical dynamics and intermolecular interactions in complex systems comes from experiments that measure large ensembles of molecules. Subtle differences that may exist in these properties from molecule to molecule are obscured in the ensemble average. In contrast, single molecule measurements make it possible to observe such phenomena as the differences in the activity of individual enzyme molecules, and to characterize the molecular-scale properties of biological systems, polymers, thin films, and other kinds of nanostructured material with a level of detail that would be impossible to achieve using traditional methods. From a more practical perspective, experimental techniques involving single molecule spectroscopy are leading to the development of faster, more sensitive, more compact chemical analysis tools that can be applied to genomics research, clinical diagnostics, environmental science, high throughput screening, and other areas of biochemical analysis. For example, the traditional way to analyze a multicomponent mixture is to perform a chemical separation, and many powerful chromatographic and electroporetic tools exist to accomplish this goal. However, these techniques often lack the speed and sensitivity that is needed for such demanding applications as the screening of large libraries of compounds for new drugs. By analyzing the sample a single molecule at a time it is possible to resolve the different components of a mixture in only a few seconds or less, even when the analyte molecules are present at trace concentration levels.