College of ChemistryDepartment of ChemistryDept of Chemical and Biomolecular Engineeringbg image
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Chemistry Faculty

Paul Alivisatos

A. Paul Alivisatos

Samsung Distinguished Professor in Nanoscience and Nanotechnology Research

Professor of Chemistry

email: alivis@berkeley.edu
office: D43 Hildebrand
office phone: 510.643.7371
office fax: 510.642.6911
lab: D86-D79 Hildebrand
lab phone: 510.642.2148, 643.4078
student/post doc office: D81 and D45 Hildebrand

Research Group URL
Recent Publications

(*photo by LBL photographer Roy Kaltschmidt)

Research Interests

Prof. Alivisatos' research concerns the structural, thermodynamic, optical, and electrical properties of colloidal inorganic nanocrystals. He investigates the fundamental physical and chemical properties of nanocrystals and also works to develop practical applications of these new materials in biomedicine and renewable energy.

Nanocrystals: Building Blocks for Solid State Chemistry and Materials Design

Nanometer size inorganic crystals are playing an increasingly important role in solid state physics, chemistry, materials science, and even biology. Many fundamental properties of a crystal (e.g., ionization potential, melting point, band gap, saturation magnetization) depend upon the solid being periodic over a particular length scale, typically in the nm regime. By precisely controlling the size and surface of a nanocrystal, its properties can be tuned. Using techniques of molecular assembly, new nanocrystal based materials can in turn be created.

Scaling Laws

As the number of atoms in a cluster increases, there is a critical size above which one particular bonding geometry; characteristic of an extended solid "locks in." As more atoms are added, the total volume and the number of surface atoms change, but the basic nature of the chemical bonds in the cluster does not. In this regime, the properties of nanocrystals vary smoothly, slowly extrapolating to bulk values, according to scaling laws. Many scaling laws have been hypothesized, a few are verified. For instance, the band gap of a semiconductor, such as Si, InAs, or CdSe, all increase with size, roughly as 1/r2, and their melting temperatures all decrease with size, roughly as 1/r, and these observations can be described well theoretically. Other size dependent scaling laws are topics of current research: How long does it take for a crystal to isomerize between two stable bonding geometries? How do the selection rules for absorption and emission of light depend upon the crystal size (translational symmetry)? What is the largest crystal that can be made defect free? In our fundamental studies of nanocrystal physics, we employ a wide range of spectroscopic and structural experimental tools, as well as computer simulation.

Synthesis

The ability to make nanocrystals of high quality (uniform size, no defects except the ones we want, designed surface, etc.) is key to this area of science, and also interesting in its own right. We grow nanocrystals by injecting organometallic precursors into pure, hot surfactants. Some important questions of solid state chemistry can be addressed in the synthesis of nanocrystals. How does nucleation of a solid occur? What governs the rate of growth of a crystal? What is the stress and strain at the interface between a core and a shell of different materials? In addition to fundamental studies of nanocrystal synthesis, we are interested in developing automated, self-correcting nanocrystal syntheses, surface derivitization, and methods for nanocrystal characterization and assembly.

Materials Design Targets

Biography

Paul Alivisatos received a Bachelor's degree from the University of Chicago in 1981, and a Ph.D. in Physical Chemistry under the supervision of Charles Harris from the University of California, Berkeley in 1986. He was a postdoctoral fellow with Louis Brus at AT&T bell Labs. He joined the University of California, Berkeley as a faculty member in 1988, where he is presently Professor of Chemistry and Materials Science, and the Larry and Diane Bock Professor of Nanotechnology. He is currently Deputy Director at the Lawrence Berkeley National Laboratory (2008- ) and Scientific Director, Molecular Foundry, Inorganic Nanostructures Facility (2006- ). Previously at LBNL he has served as Director of the Materials Sciences Division (2002-2008) and Associate Laboratory Director for Physical Sciences (2005-2008). He has received numerous awards including: Coblentz Award (1994); Wilson Prize (1994); Chancellor's Professor, University of California, Berkeley (1998-2001); Outstanding Young Investigator Award (1999); ACS Award in Colloid and Surface Chemistry (2004); Member, National Academy of Sciences (2004); Member, American Academy of Arts and Sciences (2004); Rank Prize (2006); University of Chicago Distinguished Alumni Award (2006); Eni Italgas Prize for Energy and Environment (2006); Ernest Orlando Lawrence Award (2007); and the Kavli Distinguished Lectureship in Nanoscience (2008). He is the founding editor of Nano Letters, a journal of the American Chemical Society.

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