Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 6: Electronic Structure and Spectroscopy I
CPP 6.6: Vortrag
Montag, 27. März 2006, 16:00–16:15, ZEU 114
Interferometric Pump-Probe Spectroscopy of Single Gold Nanoparticles — •Markus Lippitz1,2, Meindert A. van Dijk1, and Michel Orrit1 — 1MoNOS, Huygens Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands — 2present address: Institut für physikalische Chemie, Universität Mainz, Jakob Welder-Weg 11, 55099 Mainz, Germany
We report the first time-resolved absorption measurements of single gold nanoparticles, with a sensitive common-path interferometer [1,2]. The variation of the plasmon resonance after absorption of a near-infrared pump pulse is probed in the visible wavelength range. It can be separated in two parts: The prompt part of the signal arises from an increased plasmon resonance width due to hot electrons, and provides high-contrast images of particles as small as 10 nm. On a longer timescale, an oscillating transient (period about 16 ps for 50 nm diameter) reveals mechanical vibrations of the particle by periodic shifts of the plasmon frequency.
The selection of individual particles reveals the full heterogeneity of the ensemble, and the intrinsic damping of the vibrations, which is hidden in bulk measurements. Besides the fundamental breathing mode already seen in ensembles, we find a new mode at lower frequency involving shear deformation. Ultra-fast laser spectroscopy of single gold particles opens new insight into the mechanical properties of nanometer-sized objects.
[1] M.A. van Dijk et al., Acc. Chem. Res., 2005, 38, 594
[2] M.A. van Dijk et al., Phys. Rev. Lett., accepted, preprint cond-mat/0506401