[CCoE Notice] IEEE Seminar * March 23, 2012 * Xiaoqin (Elaine) Li * UT Austin

[Lewis, Lindsay R]

 ***** Seminar *****
Center for Integrated Bio and Nano Systems
                                                                                Houston Chapter of IEEE Nanotechnology Council and Houston Chapter of IEEE Magnetics Society
Friday, March 23, 2012
12:30 p.m. (Refreshments served at noon)
Room: W122 Building D3

                                    Light Scattering from the Collective Modes of Electrons

Dr. Xiaoqin (Elaine) Li

Department of Physics
The University of Texas at Austin

Abstract:



A powerful approach for investigating properties of matter is light scattering. In this talk, I will discuss how scattering is used to probe collective modes of electrons in two distinct systems.



The first example focuses on light scattering from collective electron oscillations in metals called plasmons. We investigated a low-symmetry heterogeneous nanostructure comprised of simple yet distinct gold nanoparticles (NPs): a sphere and a rod. When the two NPs are coupled via near field interaction, a Fano resonance emerges from the interference between the dark, quadrupole mode of the rod and the bright, dipolar mode of the sphere. Polarization sensitive and tomography-like scattering measurements from different directions allowed us to determine the relative position and orientation between the two NPs on the nanometer scale. We coined the term "plasmonic protractor" to suggest this simple nanostructure may be useful for studying in-situ conformational changes such as rotation and bending at the single molecule level.


The second example focuses on light scattering from collective spin oscillations in ferromagnetic materials called magnons. Magnons, or spin waves, are the normal modes of magnetic excitations, just as phonons are the normal modes of lattice vibrations. Using a technique called micro Brillouin light scattering, we were able to spatially map out the spin wave intensity in magnetic microstructures.




Bio:
Dr. Xiaoqin (Elaine) LI obtained her Master degree in Electrical Engineering in 2002 and her PhD in physics in 2003 from the University of Michigan. Following a postdoctoral position at JILA, Colorado, she joined the physics department at University of Texas-Austin in 2007. Her group is currently exploring unique properties of metallic and hybrid nanostructures, semiconductor quantum dots and quantum wells, spin waves in micromagnetic devices using a variety of light scattering techniques and advanced nonlinear spectroscopy methods such as multidimensional Fourier transform spectroscopy. In recent years, Dr. Li has received a number of awards which include the Sloan fellowship, the NSF CAREER award and the Presidential Early Career Award for Scientists and Engineers (PECASE).

Contact Prof. Jiming Bao (jbao at uh.edu<mailto:jbao at uh.edu>) if you would like to arrange for a time to meet with Prof. Li.
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