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Materials Science

Dr. Mikhail Zamkov's research focuses on the electronic, chemical and optical properties of hybrid nanoscale materials prepared with sub-nanometer precision by means of colloidal syntheses. Such semiconductor or metal nanoparticles can be chemically manipulated like large molecules and can be coupled to each other or can be incorporated into different types of inorganic or organic matrices. The ease of manipulating both the dimensions of the individual particles as well as their arrangement in a complex interacting structure makes colloidal nanostructures well-suited for studies of size/structure-dependent quantum-mechanical interactions and as ideal building blocks for nanoscale engineering.

 

Specifically, experimental work in Dr. Zamkov's group addresses four major areas: (1) synthesis and characterization of novel nanoscale building blocks, (2) elucidation of their fundamental optoelectronic properties, (3) design and demonstration of functional nanoscale devices and integrated nanosystems, and (4) exploration of the interface/communication between biological systems and nanoscale devices. This research by is highly interdisciplinary, involving concepts and techniques from biology, chemistry, physics and the engineering sciences to achieve their goals.

 

  • Our method for the solid state based thin films of nano-particles for optoelectronic applications

Kinder, E.; Moroz, P.; Diederich, G.; Johnson, A.; Kirsanova, M.; Nemchinov, A.; O'Connor, T.; Roth, D.; Zamkov, M., "Fabrication of all-inorganic nanocrystal solids through matrix encapsulation of nanocrystal arrays." J. Am. Chem. Soc. 2011, 133, 20488–20499.

 

 

Dr. Liangfeng Sun's research group fosters interdisciplinary research including diverse topics of physics, chemistry and engineering of nanostructured materials. The goal of his research team is to discover and investigate the novel physical and chemical properties of the materials in the nanometer scale, and apply them in photochemistry, bio-imaging, light-emitting devices and solar cells.

Dr. Sun's publications include one paper in Nature Nanotechnology, one paper in Physical Review Letters, and six papers in Nano Letters. His PbSe-nanocrystal-based solar cells rank among the highest performing nanocrystal-based solar cells reported to date. His record-brightness PbS-nanocrystal-based light-emitting diodes emit infrared light with tunable wavelength from 800 nm to 1800 nm, which will find broad application in free space and fiber optical communication, night vision and sensing.

The students in Dr. Sun's group learn and master many experimental techniques for nanomaterial research, including electron microscopy (such as TEM and SEM), UV-Vis-IR spectroscopy, laser technology, synthesis of nanostructured materials, optoelectronic device fabrication and testing. Moreover, they participate in planning future research and building up the lab, where they gain significant critical-thinking and problem-solving skills. These will be their assets when they pursue their future career either in academics or in industry.

Recent work:

Ghadendra B. Bhandari, Kamal Subedi, Yufan He, Zhoufeng Jiang, Matthew Leopold, Nick Reilly, H. Peter Lu, Alexey T. Zayak, and Liangfeng Sun, "Thickness-Controlled Synthesis of Colloidal PbS Nanosheets and Their Thickness-Dependent Energy Gaps", Chemistry of Materials, 26 (19) 5433-5436 (2014)  

 

 

Farida Selim is the inventor of Accelerator based positron annihilation spectroscopy (APAS) technique, known today as Gamma induced positron spectroscopy (GIBS). Instead of using positron particles, the technique uses MeV gamma rays from accelerators to create positrons inside the sample by pair production and conduct Doppler broadening and positron lifetime measurements. For more information read some of Selim early publications (1), (2), (3).  

The technique has been recently adopted to build a unique materials research facility at the superconducting accelerator facility at Dresden, Germany and named as GIBS, ELBE – Center for High-Power Radiation Sources - Helmholtz-Zentrum Dresden-Rossendorf, HZDR. The technique has extended PAS application to many new fields in materials Science.

  • Dr. Selim is active in the community of researchers studying ZnO.

  • In 2012, Selim group also developed a new optical spectrometer “x-ray induced luminescence spectroscopy” that substantially enhanced study of luminescence centers and scintillation properties in photonic materials.

 

 

 

 

 

 

 

Recent work:   Discovery dramatically improves electrical conductivity in perovskite SrTiO3
Nov 14, 2013
by Marianne C. Tarun, Farida A. Selim, and Matthew D. McCluskey
More information: Persistent Photoconductivity in Strontium Titanate, Phys. Rev. Lett. 111, 187403 (2013)

 

 

The research of Dr. Zayak's group is focused on atomistic simulations within density functional theory, and the use of advanced electronic structure software like PWSCF, SIESTA and PARSEC for computing crystalline or molecular properties with the goal of understanding basic mechanisms in materials chemistry. Modern computational theory is remarkably versatile: in addition to the widely applicable DFT that provides accurate chemical properties in most cases, there are more advanced methods that extend boundaries of DFT for describing more complex phenomena like, for example, van der Waals interactions or electronic excitations.


    One of the most important aspects of our research is the ability to directly compare theory with experimental data. Raman spectroscopy, for example, utilizes interactions of light with atomic vibrations, providing unique ‚”fingerprints” of any chemical species. Theory provides insight into electronic properties underlying this technique. Using first-principles calculations, we can analyze spectral information to the point of probing not only a chemical species itself, but also its immediate chemical environment. The ability to understand nano-scale spectroscopy opens remarkable prospects for new discoveries.

Recent work:

A. K. Kuhlman and A. T. Zayak, “Revealing Interaction of Organic Adsorbates with Semiconductor Surfaces Using Chemically Enhanced Raman”, J. Phys. Chem. Lett., 5 (6) 964-968 (2014)