Localized and Propagating Plasmons in Metal Films with Nanoholes
Artikel i vetenskaplig tidskrift, 2013

The occurrence of plasmon resonances in thin (similar to 20 nm) Al and Au films, perforated with nanoholes, was studied. In both metals, two 9 plasmon resonances were observed: (i) A surface plasmon polariton mode associated with a maximum in extinction and (ii) a localized resonance in the nanohole associated with a minimum in extinction. By varying the diameter of the nanoholes, the scaling of the peak positions of the plasmon resonances was determined as a function of hole diameter. In the large nanohole limit, the plasmon peak positions depend only on the nanohole diameter being independent of the material. On the other hand, for small nanoholes the plasmon peak positions are material and size dependent. In contrast to Al films where the localized plasmons can be excited from the near-IR to the UV, no plasmon resonances were observed for Au at energies above the interband threshold (2.4 eV). The interaction between a distinct interband transition in Al at 1.5 eV and the localized plasmon resonance is considered in detail. We observe for the first time experimentally a noncrossing behavior of the interband transition and the localized plasmon resonance. The energy (size) dependence of surface plasmon peak width, being a measure for the decay/damping of the latter, is very different for the two metals. This can be explained by considering the different decay mechanisms active in the two metals. Apart from these basic plasmonics results, we test the potential of using the shifts of the plasmon resonances in perforated Al films to follow the atmospheric oxidation/corrosion kinetics of Al. The results are quantified by model calculations. The obtained kinetic law for the oxide growth is in good agreement with a previous XPS study on plain Al films. This suggests that the nanohole-induced plasmon resonances can be a sensitive and simple measure for Al corrosion and metal corrosion in general.

resonance

surface plasmon polariton

phase-transition

colloidal lithography

nanoholes

gold

Localized surface plasmon resonance

nanoparticles

aluminum

gold

enhanced raman-scattering

nanodisks

optical-properties

arrays

metamaterials

Författare

Markus Schwind

Chalmers, Teknisk fysik, Kemisk fysik

Bengt Herbert Kasemo

Chalmers, Teknisk fysik, Kemisk fysik

Igor Zoric

Chalmers, Teknisk fysik, Kemisk fysik

Nano Letters

1530-6984 (ISSN) 1530-6992 (eISSN)

Vol. 13 1743-1750

Ämneskategorier

Fysik

Nanoteknik

DOI

10.1021/nl400328x