title: Fan-shaped gold nanoantennas above reflective substrates for surface-enhanced infrared absorption (SEIRA).
abstract: Here, we report a new nanoantenna for surface-enhanced infrared absorption (SEIRA) detection, consisting of a fan-shaped Au structure positioned at a well-specified distance above a reflective plane with an intervening silica spacer layer. We examine how to optimize both the antenna dimensions and the spacer layer for optimal SEIRA enhancement of the C-H stretching mode. This tunable 3D geometry yields a theoretical SEIRA enhancement factor of 10(5), corresponding to the experimental detection of 20-200 zeptomoles of octadecanethiol, using a standard commercial FTIR spectrometer. Experimental studies illustrate the sensitivity of the observed SEIRA signal to the gap dimensions. The optimized antenna structure exhibits an order of magnitude greater SEIRA sensitivity than previous record-setting designs.
authors.affiliation: Department of Chemistry, ‡Department of Physics and Astronomy, §Department of Electrical and Computer Engineering, and ⊥Laboratory for Nanophotonics, Rice University , 6100 Main Street, Houston, Texas 77005, United States.
authors.forename: Lisa V
authors.initials: LV
authors.lastname: Brown
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.forename: Ke
authors.initials: K
authors.lastname: Zhao
authors.forename: Bob Y
authors.initials: BY
authors.lastname: Zheng
authors.forename: Peter
authors.initials: P
authors.lastname: Nordlander
authors.forename: Naomi J
authors.initials: NJ
authors.lastname: Halas
keywords: FTIR; SEIRA; alkanethiols; nanoantennas; reflection