Simultaneous Chemical and Refractive Index Sensing in the 1-2.5 μm Near-Infrared Wavelength Range on Nanoporous Gold Disks.
Near-infrared (NIR) absorption spectroscopy provides molecular and chemical information based on overtones and combination bands of the fundamental vibrational modes in the infrared wavelengths. However, the sensitivity of NIR absorption measurement is limited by the generally weak absorption and the relatively poor detector performance compared to other wavelength ranges. To overcome these barriers, we have developed a novel technique to simultaneously obtain chemical and refractive index sensing in 1-2.5 μm NIR wavelength range on nanoporous gold (NPG) disks, which feature high-density plasmonic hot-spots of localized electric field enhancement. For the first time, surface-enhanced near-infrared absorption (SENIRA) spectroscopy has been demonstrated for high sensitivity chemical detection. With a self-assembled monolayer (SAM) of octadecanethiol (ODT), an enhancement factor (EF) of up to ∼10(4) has been demonstrated for the first C-H combination band at 2400 nm using NPG disk with 600 nm diameter. Together with localized surface plasmon resonance (LSPR) extinction spectroscopy, simultaneous sensing of sample refractive index has been achieved for the first time. The performance of this technique has been evaluated using various hydrocarbon compounds and crude oil samples.
Department of Electrical and Computer Engineering, University of Houston , Houston, Texas 77204, United States.|Department of Biomedical Engineering, University of Houston , Houston, Texas 77204, United States.|Department of Chemistry, University of Houston , Houston, Texas 77204, United States.|Program of Materials Science and Engineering, University of Houston , Houston, Texas 77204, United States.
Wei-Chuan
WC
Shih
Department of Electrical and Computer Engineering, University of Houston , Houston, Texas 77204, United States.
Greggy M
GM
Santos
Department of Electrical and Computer Engineering, University of Houston , Houston, Texas 77204, United States.
Fusheng
F
Zhao
Department of Electrical and Computer Engineering, University of Houston , Houston, Texas 77204, United States.
Oussama
O
Zenasni
Department of Electrical and Computer Engineering, University of Houston , Houston, Texas 77204, United States.
Md Masud Parvez
MM
Arnob
Nanoporous gold disks/nanoparticles; hydrocarbon sensing and identification; near-infrared molecular fingerprinting; plasmonics; surface-enhanced near-infrared absorption spectroscopy; vibrational molecular overtones and combination bands