Faculty

Todd D. Krauss

Professor of Chemistry
Professor of Optics

Chair of Chemistry Department
PhD in Applied Physics, Cornell University, 1998

465 Hutchinson
(585) 275-5093
krauss@chem.rochester.edu

Office Hours: By appointment

Website

Short Biography

Professor Krauss received his BS, MS, and PhD in applied physics all from Cornell University, the latter under Frank Wise. Upon graduation in 1998, he moved to Columbia University, serving as a postdoctoral fellow under Louis Brus until 2000 when he joined the chemistry faculty at the University of Rochester as an assistant professor. In 2006, Krauss was promoted to the rank of associate professor of chemistry and in 2008 he received a joint appointment with optics. In 2010 Krauss was promoted to professor of chemistry and optics. The author of more than 75 publications in peer reviewed journals, Krauss also lectures locally and nationally on the optics of nanometer scale materials. Krauss is the director of the Rochester Advanced Materials Program at the University, and most recently was named a fellow of the American Physical Society (2012).

Research Overview

Professor Krauss' main research area concern understanding the fundamental properties of materials with a size in between individual molecules and macroscopic objects. These nanometer scale materials have physical characteristics that are strong functions of their size and shape, with properties that can be easily manipulated to address a given application. His group's investigations in this area are currently focused on fundamental photophysical studies of carbon nanotubes and semiconductor nanocrystal quantum dots, and the integration of these materials into both novel devices for solar energy conversion and biological sensors. These studies are highly interdisciplinary, and lie at the interface between chemistry, optics, physics, applies physics, and materials science.

Carbon nanotubes consist of a hexagonal network of carbon atoms rolled up into a cylinder. Nanotubes are typically tens to hundreds of microns long, while their diameter is usually only around 1 nanometer. The quantum confinement of electrons around the nanotube results in unexpected properties. For example, carbon nanotubes can be either metallic or semiconducting, depending on the diameter and helicity of the carbon lattice. We are concerned with determining fundamental electronic and optical characteristics of single carbon nanotubes, as well as the design of carbon nanotube membranes for artificial photosynthesis applications (Figure 1). These investigations are carried out using atomic force microscopy, as well as single molecule and ultrafast optical spectroscopy.

Fig. 1

Figure 1. Images of a carbon nanotube membrane for water splitting applications. (A) Scanning electron microscope image of vertically aligned nanotubes. The scale bar is 10 µm and the NTs are approximately 150 µm tall. (B) Nanotube arrays following epoxy impregnation to form the freestanding membrane. Scale bar is 10 µm and approximately 20 µm of NT length are exposed above the bulk. (Inset) Photograph of the final, self-supporting membrane approximately 2.5 cm2

Fig. 2

Figure 2. Fluorescence from different sized CdSe quantum dots.
Inorganic semiconductor particles containing a few thousand atoms, known as semiconductor quantum dots (Figure 2) also have unique electronic and optical properties. Using state-of-the-art experimental techniques (electrostatic force microscopy and single molecule optical spectroscopy), we are investigating the optical emission characteristics of individual quantum dots and the effect of permanent charges on this emission. We are also studying the fundamental inorganic reaction mechanism that describes the initial formation of quantum dots from molecular precursors.

A significant remaining challenge for materials chemistry is to connect nanometer-sized materials to the macroscopic world. To that end, we are also developing simple synthetic methods to make novel nanocrystals and carbon nanotubes, are exploring chemical modification of their surfaces, and are looking to make integrated nano-systems from these nanoparticle building blocks. Our eventual goal is to build devices that can take solar energy and convert it to clean burning fuels such as hydrogen using nanomaterials as the basis for the device. This latter work is done in collaboration with Professors Bren and Eisenberg from the University of Rochester.

Selected Publications

  • Smyder, J., Peterson, J.J., Amori, A., Krauss, T. D. "The Influence of Continuous vs. Pulsed Laser Excitation on Single Quantum Dot Photophysics," Phys. Chem. Chem. Phys. 2014, DOI: http://dx.doi.org/10.1039/C4CP01395F.
  • Schäfer, S., Cogan, N.M., Krauss, T. D. "Spectroscopic investigation of electrochemically charged individual (6,5) single walled carbon nanotubes," Nano Lett. 2014, 14, 3138-3144.
  • Cogan, N.M.B., Bowerman, C.J., Nogaj, L.J.,Nilsson, B.L., Krauss, T. D. "Selective Suspension of Single-Walled Carbon Nanotubes using β-Sheet Polypeptides," J. Phys. Chem. C 2014, 118, 5935-5944.
  • Pilgrim, G.A., Leadbutter, J.W., Qiu, F., Siitonen, A.J., Pilgrim, S.M., Krauss, T. D. "Electron Conductive and Proton Permeable Vertically Aligned Carbon Nanotube Membranes," Nano Lett. 2014, 14, 1728-1733.
  • Lee, A.J., Asher, W.B., Stern, H.A., Bren, K.L., Krauss, T. D. "Single-molecule analysis of cytochrome c folding by monitoring the lifetime of an attached fluorescent probe," J. Phys. Chem. Lett 2013, 4, 2727-2733.
  • Han, Z., Qiu, F., Eisenberg, R., Holland, P.L., Krauss, T. D. "Robust Photogeneration of H2 in Water Using Semiconductor Nanocrystals and a Nickel Catalyst," Science 2012, 338, 1321-3124.
  • Lee, A. J., Wang, X., Carlson, L. J., Smyder, J. A., Tu, X., Zheng, M., Krauss, T. D. "Bright Fluorescence from Individual Single-Walled Carbon Nanotubes," Nano Lett. 2011, 11, 1636-1640.
  • Evans, C. M., Evans, M., Krauss, T. D. "Mysteries of TOPSe Revealed: Insights into Quantum Dot Nucleation," J. Am. Chem. Soc. 2010, 132, 10973-10975.
  • Wang, S., Khafizov, M., Tu, X., Zheng, M., Krauss, T.D. "Multiple Exciton Generation in Single-Walled Carbon Nanotubes," Nano Lett. 2009, 10, 2381-2386.
  • Evans, C. M., Guo, L., Peterson, J. J., Maccagnano, S., Krauss, T. D. "Ultra-bright PbSe Magic Sized Clusters," Nano Lett. 2008, 8, 2896-2899.
  • Huang, L., Krauss, T. D. "Quantized bimolecular Auger recombination of excitons in single-walled carbon nanotubes," Phys. Rev. Lett. 2006, 96, 057407.
  • Peterson, J. J., Krauss, T. D. "Fluorescence Spectroscopy of Single Lead Sulfide Quantum Dots," Nano Lett. 2006, 6, 510-514.
  • Hartschuh, A., Pedrosa, H. N., Novotny, L., Krauss, T. D. "Simultaneous Fluorescence and Raman Scattering from Individual Single-Walled Carbon Nanotubes," Science 2003, 301, 1354-1356.
  • Du, H., Chen, C.L., Krishnan, R., Krauss, T.D., Harbold, J.M., Wise, F.W., Thomas, M.G., Silcox, J. "Optical properties of colloidal PbSe nanocrystals," Nano. Lett. 2002, 2, 1321-1326.