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High-Contrast Infrared Absorption Spectroscopy via Mass-Produced Coaxial Zero-Mode Resonators with Sub-10 nm Gaps.
- Source :
-
Nano letters [Nano Lett] 2018 Mar 14; Vol. 18 (3), pp. 1930-1936. Date of Electronic Publication: 2018 Feb 22. - Publication Year :
- 2018
-
Abstract
- We present a wafer-scale array of resonant coaxial nanoapertures as a practical platform for surface-enhanced infrared absorption spectroscopy (SEIRA). Coaxial nanoapertures with sub-10 nm gaps are fabricated via photolithography, atomic layer deposition of a sacrificial Al <subscript>2</subscript> O <subscript>3</subscript> layer to define the nanogaps, and planarization via glancing-angle ion milling. At the zeroth-order Fabry-Pérot resonance condition, our coaxial apertures act as a "zero-mode resonator (ZMR)", efficiently funneling as much as 34% of incident infrared (IR) light along 10 nm annular gaps. After removing Al <subscript>2</subscript> O <subscript>3</subscript> in the gaps and inserting silk protein, we can couple the intense optical fields of the annular nanogap into the vibrational modes of protein molecules. From 7 nm gap ZMR devices coated with a 5 nm thick silk protein film, we observe high-contrast IR absorbance signals drastically suppressing 58% of the transmitted light and infer a strong IR absorption enhancement factor of 10 <superscript>4</superscript> ∼10 <superscript>5</superscript> . These single nanometer gap ZMR devices can be mass-produced via batch processing and offer promising routes for broad applications of SEIRA.
Details
- Language :
- English
- ISSN :
- 1530-6992
- Volume :
- 18
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Nano letters
- Publication Type :
- Academic Journal
- Accession number :
- 29437401
- Full Text :
- https://doi.org/10.1021/acs.nanolett.7b05295