title: Structure of plasmonic aerogel and the breakdown of the effective medium approximation.
abstract: A method for making aerogel doped with gold nanoparticles (GNPs) produces a composite material with a well-defined localized surface plasmon resonance peak at 520 nm. The width of the extinction feature indicates the GNPs are well dispersed in the aerogel, making it suited to optical study. A simple effective medium approximation cannot explain the peak extinction wavelengths. The plasmonic field extends on a scale where aerogel cannot be considered isotropic, so a new model is required: a 5 nm glass coating on the GNPs models the extinction spectrum of the composite material, with air (aerogel), methanol (alcogel), or toluene filling the pores.
authors.affiliation: Department of Physics, University of Bath, Bath, United Kingdom.
authors.forename: Michael D W
authors.initials: MD
authors.lastname: Grogan
authors.forename: Susannah C
authors.initials: SC
authors.lastname: Heck
authors.forename: Katie M
authors.initials: KM
authors.lastname: Hood
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Maier
authors.forename: Tim A
authors.initials: TA
authors.lastname: Birks