En-Shinn Wu

Associate Professor

Ph.D. Cornell University, 1978

Contact Information
Room 413, Physics Bldg.
Department of Physics
Univ. Maryland Baltimore County
1000 Hilltop Circle
Baltimore, MD 21250

Phone:	(410) 455-2526
Email:	ewu@umbc.edu

Research Interests

The principal research interest in our laboratory is to study the dynamic behavior of polymer chains, with an aim to understand the matrix structures and the internal organization of polymers and biopolymers. Our experimental approach is to measure the diffusion coefficient of fluorescently labelled molecules with the technique of fluorescence recovery after photobleaching (FRAP). Recent FRAP measurements include the diffusion of PEO in the presence of electrolytes, the selfdiffusion of polystyrene in semi-dilute solutions and the mobility of ubiquinone in multilayer liquid crystals.

Our most recent area of study has been the application of two-photon excitations on photopolymers. Under sufficient illumination intensity, electronic excitations may be produced by simultaneous absorption of two photons, each providing half the energy of the transition. The excitation is localized in a 3-d spot defined by the focal volume of the light source. By scanning this spot in 3-d it is possible to expose arbitrary patterns in photopolymers. With this technique we have produced microlithographic structures with half micron wide trenches of very high aspect ratio. We are exploring the potential utility of this technique in areas of 3-d data storage.

Selected Publications

Two-photon Lithography for Microelectronic Application

E. S. Wu, J. Strickler, R. Harrel and W. Webb,

1992, SPIE Proc. 1674, 776

Polymer Self-diffusion in Nal-Poly(ethylene Oxide) Electrolytes

E. S. Wu, J. H. Shibata and F. W. Wang,

1992, Polymer 33, 1014

The Mobility of a Fluorescent Ubiquinone in Model Membranes, Relevance to Mitochondrial Electron Transport

B. Chazotte, E. S. Wu and C. Hackenbrock, ","

1991, Biochem. Biophys. Acta 1058, 400

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Department of Physics - 1000 Hilltop Circle, Baltimore, MD 21250