INOR 487 |
| Changing the intensity and wavelength of a femtosecond laser, we can modify the shape of assembled nanoprisms prepared with nanosphere lithography (NSL) technique. With a modified NSL technique, we can synthesize large area of monodisperse nanoprisms. As the power of 400 nm femtosecond laser irradiation increases, the prismatic particle apex begins to round and the overall particle shape changes from prismatic to spherical with a tripodal intermediate. The observed shape changes are driven by the thermodynamic lowering of the surface energy of the nanoparticles. First, the change of high surface energy apex is observed. This is followed by the formation of three small hemispheres at the apex locations. Finally, as the atoms given more energy, the three hemispheres are transformed into one large sphere that has the lowest surface energy. By exciting the surface plasmon absorption at 700 - 800 nm with a femtosecond laser, we observe different phenomena. |
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Nanoscience: Characterization
2:00 PM-5:00 PM, Monday, 11 September 2006 Moscone Center -- Room 309, Oral
Division of Inorganic Chemistry |