title: Metal nanoparticle ensembles: tunable laser pulses distinguish monomer from dimer vibrations.
abstract: Resonant interaction of laser pulses with plasmons is used to identify vibrations associated with isolated spheres and pairs of contacting spheres in a system of gold nanoparticles. The optical pulses generate coherent mechanical oscillations of both monomers and dimers in the 5-150 GHz range, the amplitudes of which exhibit a strong enhancement when the laser central wavelength is tuned to resonate with the corresponding plasmon. Because of the resonant selection in the excitation process, the widths of the acoustic modes are significantly smaller than broadening caused by the spread in radii in the ensemble.
authors.affiliation: Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina.
authors.forename: Pablo M
authors.initials: PM
authors.lastname: Jais
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Murray
authors.forename: Roberto
authors.initials: R
authors.lastname: Merlin
authors.forename: Andrea V
authors.initials: AV
authors.lastname: Bragas
mesh_terms: D000162:Acoustics; D019281:Dimerization; D006046:Gold / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D009991:Oscillometry / Q000379:methods; D010825:Physics / Q000379:methods; D011108:Polymers / Q000737:chemistry; D020349:Surface Plasmon Resonance; D014732:Vibration
chemical_list: D008670:Metals; D011108:Polymers; D006046:Gold