Two-Scale Structure for Giant Field Enhancement: Combination of Rayleigh Anomaly and Colloidal Plasmonic Resonance

Molecular overtones stretching modes that occupy the near-infrared (NIR) are weak compared to the fundamental vibrations. Here we report on the enhancement of absorption by molecular vibrations overtones via electromagnetic field enhancement of plasmonic nanoparallelepipeds comprising a square lattice. We explore numerically, using finite element method (FEM), gold metasurfaces on a transparent dielectric substrate covered by weakly absorbing analyte supporting N-H and C-H overtone absorption bands around 1.5 μ m and around 1.67 μ m, respectively. We found that the absorption enhancement in N-H overtone transition can be increased up to the factor of 22.5 due to the combination of localized surface plasmon resonance in prolonged nanoparticles and lattice Rayleigh anomaly. Our approach may be extended for sensitive identification of other functional group overtone transitions in the near-infrared spectral range.

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Nonlinear Modulation of Plasmonic Resonances in Graphene-Integrated Triangular Dimers at Terahertz Frequencies

Materials ◽

10.3390/ma12152466 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2466

Author(s):

Quan Li ◽

Shuang Wang ◽

Tai Chen

Keyword(s):

Strong Field ◽

Field Enhancement ◽

Subwavelength Structures ◽

Plasmonic Resonance ◽

Nonlinear Conductivity ◽

Resonance Modes ◽

Terahertz Frequencies ◽

Terahertz Sensing ◽

Nonlinear Modulation ◽

A Charge

Metamaterials made from artificial subwavelength structures hold great potential in designing functional devices at microwave, terahertz, infrared, and optical frequencies. In this work, we study the active switching effect of the plasmonic resonance modes in triangular dimer (DTD) structure using graphene in the terahertz regime. The sole DTD structure can only support a dipolar bonding dimer plasmonic (BDP) mode, whose field enhancement factor at the gap center can reach 67.4. However, with a metallic junction in the dimer, the BDP mode switches to a charge transfer plasmonic (CTP) mode. When changing the metallic junction to a graphene stripe, an active modulation effect of the CTP mode can be realized by altering the nonlinear conductivity of graphene through strong-field terahertz incidence. The proposed design is quite promising in terahertz sensing, amplitude switching and nonlinear effect enhancement, etc.

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Non-noble metal plasmonic photocatalysis in semimetal bismuth films for photocatalytic NO oxidation

Physical Chemistry Chemical Physics ◽

10.1039/c7cp04359g ◽

2017 ◽

Vol 19 (37) ◽

pp. 25610-25616 ◽

Cited By ~ 14

Author(s):

Ying Zhou ◽

Wei Li ◽

Qian Zhang ◽

Shuai Yan ◽

Yuehan Cao ◽

...

Keyword(s):

Energy Barrier ◽

Photocatalytic Oxidation ◽

Field Enhancement ◽

Low Energy ◽

No Oxidation ◽

Strongly Correlated ◽

Desorption Energy ◽

Plasmonic Resonance ◽

Bismuth Films ◽

Oxidation Of No

Field enhancement and location of plasmonic resonance peaks are strongly correlated with the size of Bi particles. The low energy barrier for the conversion of NO to NO2 and low NO2 desorption energy over Bi particles indicate that Bi films are very active for photocatalytic oxidation of NO and possess good stability.

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