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Preston T. Snee

Assistant Professor
Physical and Inorganic Chemistry

born 1972; B.S. (summa cum laude) 1995, The University of North Carolina at Chapel Hill; PhD, The University of California at Berkeley, 2002; Postdoctoral Fellow, Massachusetts Institute of Technology, 2003-2006.

My research group is focused on the study of energy transfer in semiconductor nanocrystals (NCs). We are interested in (1) constructing novel semiconductor nanocrystal material systems to engineer energy transfer processes, (2) developing imaging agents based on our NC constructs and (3) bandgap engineering of multilayered nanocrystalline materials.



Semiconductor Nanocrystals are a unique form of matter which have a size dependent absorption and emission spectra. As a consequence, the electronic structure follows the quantum “particle-in-a-box” principal- only certain distinct electronic states can be occupied as dictated by the finite size of the crystal. Strongly confined NCs have atomic like density of states and size dependent bandgaps. Further, the crystallinity and organic surface passivation of semiconducting NCs result in very efficient emission quantum yields compared to the bulk materials. As shown here, the emission wavelength can be tuned not only with size, but composition and structure as well.


Energy Transfer: We are developing methods of conjugating organic molecules to the surfaces of nanocrystals which results in efficient Förster Resonant Energy Transfer (FRET) between the photoexcited NC and the dye. In the course of this work we discovered that we could modulate the efficiency of energy transfer when we coupled a dye which has environmentally sensitive absorption spectra. The result is a naturally self-referencing fluorescent sensor.

Bioimaging: We are now building NC based multifunctional biological sensors to not only image complex biological environments, we may also learn about the local chemical environment. We are presently developing imaging / sensing agents that may be used to monitor energy consumption within a cell and detect cancer in the lymphatic system.


Multilayered Composite Materials: We are designing synthetic methods for multilayered semiconducting NCs to engineer the bandgap of these materials. We are especially interested in Type II NCs which can separate electron and hole carriers directly upon photogeneration. These materials may be useful for applications involving near to far Infrared emitters and energy conversion.

Recent Publications:

(1) Snee, P. T.; Chan, Y.; Nocera, D. G.; Bawendi, M. G. “Whispering Gallery Mode Lasing from a Semiconductor Nanocrystal Microsphere Resonator Composite” Adv. Materials,2005, 17, 1131.

(2) Chan, Y.*; Steckel, J. S.*; Snee, P. T.*; Bawendi, M.G. “Blue Lasing from a CdS Nanocrystal Laser” App. Phys. Lett., 2005, 86, 073102. Highlighted in Laser Focus World, Spectra Photonics.

(3) Wun, A. W.; Snee, P.T.; Chan, Y.; Bawendi, M. G.; Nocera, D. G. “Non-linear Transduction Strategies for Chemo/biosensing on Small Length Scales” J. Mater. Chem., 2005, 15, 2697.

(4) Caruge, J.-M.*; Chan, Y.*; Snee, P. T.; Bawendi, M. G. “Multiexcitonic State Two State Lasing in a CdSe Nanocrystal Laser” App. Phys. Lett., 2004, 85, 2460.
   

Office:
Office telephone: 312-413-2566
Laboratory telephone:
Fax: 312-996-0431
Electronic mail: sneep@uic.edu
Website: Snee Group