Background-suppressed surface-enhanced molecular detection by metamaterial infrared absorber

Atsushi Ishikawa, Takuo Tanaka

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A background-suppressed surface-enhanced molecular detection technique is experimentally demonstrated by utilizing the resonant coupling of plasmonic modes of a metamaterial absorber and Infrared (IR) vibrational modes of molecules. The fabricated metamaterial consisted of one-dimensional (1D) array of Au micro-ribbons on a thick Au film separated by an MgF2 gap layer. The surface structures were designed to exhibit an anomalous IR absorption at ∼ 3000 cm-1, which spectrally overlapped with C-H stretching vibrational modes. 16-Mercaptohexadecanoic acid (16-MHDA) was used as a test molecule, which formed a 2-nm thick self-assembled monolayer (SAM) with their thiol head-group chemisorbed on the Au surface. In the FTIR measurements, the symmetric and asymmetric C-H stretching modes of the 16-MHDA were clearly observed as Fano-like anti-resonance peaks within a broad plasmonic absorption of the metamaterial. The lowbackground detection scheme with tailored plasmonic enhancement by the metamaterial absorber dramatically improved the sensitivity down to ∼ 1.8 attomoles within the diffraction-limited IR beam spot. Our metamaterial approach thus may open up new avenues for realizing ultrasensitive IR inspection technologies.

Original languageEnglish
Title of host publicationPlasmonics
Subtitle of host publicationMetallic Nanostructures and Their Optical Properties XII
EditorsAllan D. Boardman
ISBN (Electronic)9781628411904
Publication statusPublished - Jan 1 2014
EventPlasmonics: Metallic Nanostructures and Their Optical Properties XII - San Diego, United States
Duration: Aug 17 2014Aug 21 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherPlasmonics: Metallic Nanostructures and Their Optical Properties XII
Country/TerritoryUnited States
CitySan Diego


  • Fano resonances
  • Infrared absorption spectroscopy
  • Metamaterial absorber
  • Plasmonic coupling
  • Plasmonic metamaterials
  • Plasmonic sensors
  • Self-assembled monolayers
  • Surface-enhanced infrared absorption

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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