일 시 : 2011년 3월 31일, 오후 5:00
장 소 : 500동 목암홀

-Abstract-
It is known that a pulse of high kinetic energy electrons (1-3 eV) in metals can be generated after surface exposure to external energy, such as in the absorption of light or in exothermic chemical processes. These energetic electrons are not at thermal equilibrium with the metal atoms and are called “hot electrons”. The detection of hot electrons and understanding the correlation between hot electron generation and surface phenomena are challenging questions in the surface science community. Pump-probe experiments carried out on femtosecond time scales detect the presence of hot electrons that have elastic mean free paths of approximately 10 nm in metal.
To detect and utilize the hot electron flows during exothermic chemical process, the catalytic nanodiodes were constructed from transition metal catalyst film, semiconductor layers, and Ohmic contact pads. The correlation between the chemical activity and number of hot electrons (or chemicurrent) was studied under catalytic CO oxidation and hydrogen oxidation. The nanoparticle-nanodiode hybrid systems that consist of Pt colloid nanoparticle arrays and Au/TiO2 were fabricated and utilized to detect turnover rate and hot electron generated on nanoparticle surfaces.
A continuous flow of ballistic charge carriers is generated during the absorption of photons and this process can be used to fabricate hot electron based solar cell. We found that photon energy can be directly converted to hot electron flow through the metal-semiconductor interface of Au/TiO2. The influence of localized surface plasmon resonances on the efficiency of hot electron generation will be discussed.