Zhonghua Yu

Assistant Professor

Physical chemistry

Tel. (212) 650-8361
Fax: (212) 650-6107
Office: Science Building J1114
E-mail: zyu[at]sci.ccny.cuny.edu

BS, University of Science and Technology of China
Ph.D., Columbia University


Biographical Information

Prof. Yu received his BS degree in chemical physics from the University of Science and Technology of China in 1992. After spending three years in Institute of Chemistry, Chinese Academy of Sciences, he came to US in 1995. He received his Ph.D. in chemistry from Columbia University in 2000 under the supervision of Prof. Louis E. Brus. His doctoral research focused on the development of micro-Raman spectroscopy for characterizing single-wall carbon nanotubes (SWNT), which led to the (n.m) structural determination of SWNTs. From 2001 to 2003 he was a postdoctoral fellow in Prof. Paul F. Barbara's group at University of Texas, Austin, where he conducted research in single molecule spectroscopy of inorganic nanoparticles and organic conjugated polymer molecules. He joined the City College of New York as an assistant professor of chemistry in September 2003.

Research

Physical Chemistry of Nano-Structured Materials

Nano-structured materials exhibit unique size- and shape-dependent optical and electrical properties. For example, a single-wall carbon nanotube can be either metallic or semiconducting, depending on its diameter and chirality. Prof. Yu's research is focused on the investigation of optical, electronic, and magnetic or spin properties of novel nano-structured materials, which include pure and doped semiconductor nanocrystals, carbon nanotubes, and organic conjugated polymers. The research program is highly interdisciplinary, involving physical chemistry, materials chemistry, and solid state physics, which should provide students a broad background for their future career. Specifically, three research directions will be pursued:

1. Single molecule imaging and spectroscopy of nano-materials. A macroscopic sample of nano-materials is extremely heterogeneous in terms of the size, shape, and orientation of individual components. The ensemble measurements only reveal the averaged "molecular" properties. Single molecule spectroscopy, instead, can reveal the distributions and fluctuations of "molecular" properties. We are interested in applying single molecule spectroscopy to investigate the fluorescence, Raman, and electronic energy transfer processes in nano-materials. Much effort will be devoted to developing low-temperature single molecule spectroscopy.

2. Ordered thin films of nanocrystals and nanorods. Synthetic schemes based on colloidal chemistry have been very successful in growing nanocrystals with tunable sizes and shapes. Because of the advantage of easy manipulation and processability offered by the use of colloidal nanocrystals, we are interested in fabricating ordered and/or hybrid nanocomposite films in which a key component is inorganic nanocrystals to gain useful insights into the structural and physical properties of new potential optoelectronic films. We are especially interested in the formation and characterization of liquid crystal phases composed of pure inorganic nanorods, and inorganic nanorods/organic molecules hybrid liquid crystals.

3. Electron spin dynamics of nano-materials. The electron spin properties of nano-materials have been received great attention because the spin degree of electrons could be manipulated and utilized in spintronics to make spin-based devices. Our research interest lies in the electron spin dynamics of pure and doped semiconductor nanocrystals, nanorods, and carbon nanotubes, using various static and time-resolved magneto-optical spectroscopies, including Faraday rotation, MCD, and spin-flip Raman scattering. Ordered thin films of aligned nanorods will be fabricated to facilitate the investigation of spin anisotropy.

Representative Publications

1. Li Zhang, Limin Huang, Stephen P. O'Brien, and Zhonghua Yu, "Electrostatic Doping-induced Phonon Shift of Metallic Single-Wall Carbon Nanotubes." J. Phys. Chem. C 112, 20118 (2008).

2. Li Zhang, Zhang Jia, Limin Huang, Stephen O'Brien, and Zhonghua Yu, "Low Temperature Raman Spectroscopy of Individual Single-Wall Carbon Nanotubes and Single-Layer Graphene." J. Phys. Chem. C 112, 13893 (2008).

3. Li Zhang, Saliha Aite, Zhonghua Yu. "Unique laser-scanning optical microscope for low-temperature imaging and spectroscopy." Review of Scientific Instruments 78, 083701 (2007).

4. Li Zhang, Zhang Jia, Limin Huang, Stephen O'Brien, and Zhonghua Yu. "Imaging and Raman Spectroscopy of Individual Single-Wall Carbon Nanotubes on a Large Substrate." J. Phys. Chem. C 111, 11240 (2007).

5. Zhonghua Yu, Jingbo Li, Donald B. O'Connor, Lin-Wang Wang, Paul F. Barbara, "Large Resonant Stokes Shift in CdS Nanocrystals." J. Phys. Chem. B, 107, 5670 (2003).

6. Zhonghua Yu, Louis E. Brus, "(n.m) Structural Assignments and Chirality Dependence in Single-Wall Carbon Nanotube Raman Scattering." J. Phys. Chem. B, 105, 6831 (2001).

7. Zhonghua Yu, Louis Brus, "Rayleigh and Raman Scattering from Individual Carbon Nanotube Bundles." J. Phys. Chem. B, 105, 1123 (2001).

8. Zhonghua Yu, Louis Brus, "Reversible Oxidation Effect in Raman Scattering from Metallic Single-Wall Carbon Nanotubes." J. Phys. Chem. A, 104, 10995 (2000).