Metal Nanoparticle Ensembles: Tunable Laser Pulses Distinguish Monomer from Dimer Vibrations

PABLO M JAIS; DANIEL B MURRAY; R. MERLIN; ANDREA V. BRAGAS

NANO LETTERS (PRINT)

AMER CHEMICAL SOC

Año: 2011 vol. 11 p. 3685 - 3689

1530-6984

Resonant interaction of laser pulses with plasmons is used to identify vibrations associated with isolated spheres and pairs ofcontacting spheres in a system of gold nanoparticles. The optical pulses generate coherent mechanical oscillations of bothmonomers and dimers in the 5
150 GHz range, the amplitudes of which exhibit a strong enhancement when the laser centralwavelength is tuned to resonate with the corresponding plasmon. Because of the resonant selection in the excitation process, thewidths of the acoustic modes are significantly smaller than broadening caused by the spread in radii in the ensemble.