1. Nanoscale thermal gradients activated by antenna-enhanced molecular absorption in the mid-infrared.
- Author
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Mancini, Andrea, Giliberti, Valeria, Alabastri, Alessandro, Calandrini, Eugenio, De Angelis, Francesco, Garoli, Denis, and Ortolani, Michele
- Subjects
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MOLECULAR absorption spectra , *POLYMERS , *INFRARED absorption , *OPTICAL antennas , *HEAT sinks , *PLASMONICS , *QUANTUM cascade lasers - Abstract
We investigate local heat generation by molecules at the apex of polymer-embedded vertical antennas excited at resonant mid-infrared wavelengths, exploiting the surface enhanced infrared absorption effect. The embedding of vertical nanoantennas in a non-absorbing polymer creates thermal isolation between the apical hotspot and the heat sink represented by the substrate. Vibrational mid-infrared absorption by strongly absorbing molecules located at the antenna apex then generates nanoscale temperature gradients at the surface. We imaged the thermal gradients by using a nano-photothermal expansion microscope, and we found values up to 10 K/μm in conditions where the radiation wavelength resonates with both the molecule vibrations and the plasmonic mode of the antennas. Values up to 1000 K/μm can be foreseen at maximum quantum cascade laser power. The presented system provides a promising thermoplasmonic platform for antenna-assisted thermophoresis and resonant mid-infrared photocatalysis. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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