Effect of interparticle coupling on coherent phonon oscillations of monolayer periodic plasmonic nanoparticles

PHYS 513

Wenyu Huang, Wei Qian, and Mostafa A. El-Sayed, melsayed@chemistry.gatech.edu. Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400
The prismatic gold and silver nanoparticles are synthesized in assembled monolayer periodic arrays by using the nanosphere lithography technique. Within this system, the effect of interparticle coupling on coherent phonon oscillation is studied. The coherent phonon oscillation is induced by ultrafast heating of the nanoparticle with femtosecond laser, which leads to a periodic shift of the plasmon absorption of the nanoparticles. This periodic shift can be measured by recording their transient absorption at a fixed wavelength. We find that the periods of the coherent phonon oscillation linearly dependent on the bisector of sliver and gold nanoparticles. For silver nanoparticles, the observed oscillation periods are in good agreement with theoretical calculations based on a one-dimensional standing wave model, while obvious deviation is found for the gold nanoparticle arrays. This deviation is blamed on the stronger interparticle interaction of oscillating lattice dipole between the gold nanoparticles than that between the silver nanoparticles.

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006