일 시 : 2011년 5월 23일, 5:00 PM
장 소 : 500동 L-305호

-Abstract-
This two-part presentation will discuss the dynamics of energy relaxation and energy transfer in colloidal nanocrystals of magnetic materials and doped semiconductor materials. In the first part of the talk, dynamics of spin-lattice relaxation in superparamagnetic nanocrystals and its correlation to the structural parameters of the nanocrystals will be discussed. Since the rate of spin-lattice relaxation ultimately determines the speed of devices based on spin, understanding the relationship between the structure and dynamics of spin relaxation is important. I will focus on discussing how the rate of spin-lattice relaxation is influenced by the presence of large surface/interface in nanoscale magnetic materials. The second part of the talk will discuss the dynamics of exciton-to-dopant energy transfer in Mn-doped CdS nanocrystals. The doped Mn ions can function as an efficient and long-lived sensitized energy reservoir for the excitons created in the semiconductor host, which makes the doped nanocrystal a very bright and stable chromophore. I will discuss exciton-Mn energy transfer rate correlated with the structural variation of the doped nanocrystals and its application to generate hot electrons for efficient photocatalysis.