| AVS 54th International Symposium | |
| Plasmonics Topical Conference | Tuesday Sessions |
| Session PL+BI-TuM |
| Session: | Plasmon-mediated Sensing and Biosensing |
| Presenter: | I. Zorić, Chalmers University of Technology, Sweden |
| Authors: | I. Zorić, Chalmers University of Technology, Sweden C. Langhammer, Chalmers University of Technology, Sweden E. Larsson, Chalmers University of Technology, Sweden B. Kasemo, Chalmers University of Technology, Sweden |
| Correspondent: | Click to Email |
We propose a novel nanoplasmonic sensing scheme for optical, real time, monitoring of property changes in metal nanoparticles. The property changes can be both bulk and/or surface changes induced e.g. by interaction with the surrounding medium. To sense these changes we use the localized surface plasmon resonance (LSPR) of the nanoparticle as signal transducer for remote optical readout. The high sensitivity of the LSPR (i.e. plasmon energy and extinction cross-section) to electronic, structural and shape changes, taking place in the nanoparticle, makes the latter an extremely sensitive and non-invasive probe for studies of surface and bulk changes in nanoparticles. Furthermore, since the LSPR seem to be a rather universal feature for nano-confined metallic systems the proposed sensing method is quite universal. The supported metallic nanodisks were fabricated by the hole-mask colloidal lithography method relying on electrostatically self-assembled polystyrene beads as evaporation masks. The method is suitable for fabrication of large-areas covered by nanostructures allowing for easy spectroscopic studies. The proposed sensing scheme was used to study: a) metal hydride formation in nanometer sized Pd disks exposed to hydrogen atmosphere and b) oxidation of Al nanodisks. In both cases we have quantified the optical repsonse by complementing the optical studies with gravimetric studies (QCM-D). In the latter case the same processes were studied by monitoring the frequency and dissipation shifts when Pd or Al nanoparticles, prepared on the of the quartz crystal microbalance electrode, were exposed to the hydrogen and oxidizing environment respectively. In addition, AFM and SEM studies were used to characterize the morphological changes induced during the process of interest. Te most important results include: a) hydrogen pressure-composition isotherms covering the solid solution (α) phase, the coexistence region of the α and hydride (β) phases, and finally the pure hydride phase at large hydrogen pressure. Similarities and differences to the corresponding isotherms for 2D continuous Pt films are also presented. b) Al nanoparticle oxidation kinetics in water shows an initially fast oxide growth followed by a transport limited slower kinetics accompanied by oxide shell cracking. We also show how extension of this sensing approach from nanoparticles to thin films can be made by using LSPR of the 100nm diameter holes made in continuous films.