Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.92: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Investigations on laser-beam immobilised gold nanoparticles — •Falko Brögger1, Ninet Babajani2, Malte Linn1, and Gero von Plessen1 — 1Institute of Physics (1A), RWTH Aachen University, 52056 Aachen, Germany — 2FZ Jülich, Inst. of Solid State Research (IFF-6), 52428 Jülich, Germany
The plasmon lines of chemically synthesized noble-metal nanoparticles of nearly spherical shape and approximately uniform size exhibit surprisingly large particle-to-particle variations of their resonance peak positions and line widths. The reasons for these spectral variations are still unknown. Possible explanations include faceting of the nominally spherical particles, charges and chemical effects within the suspension, and interactions with the substrate.
In this work, single gold nanoparticles suspended in an aqueous environment are trapped by an optical tweezer, and their light-scattering spectra, which are free of substrate effects, are measured. Each of the trapped nanoparticles is subsequently deposited onto a substrate using the optical tweezer and its spectrum is measured again. A comparison of the single-particle spectra shows that the particle-to-particle plasmon line variations in the aqueous suspension and the substrate-induced line changes do not seem to be correlated. Remarkably, additional line changes are observed upon drying the sample surface and covering it again with water.