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Thermal infrared near-field spectroscopy.
Andrew C Jones1, Markus B Raschke
1Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Colorado 80309, USA.
Nano Letters
|January 28, 2012
Summary
Researchers experimentally characterized the thermal near-field, revealing distinct spectral features and enhanced energy density linked to vibrational and phonon modes. This opens new avenues for controlling heat transfer and chemical nanospectroscopy.
Area of Science:
- Condensed matter physics
- Nanophotonics
- Spectroscopy
Background:
- Classical theories describe far-field thermal emission.
- The distinct properties of thermal near-fields remain experimentally unverified due to their evanescent nature.
Purpose of the Study:
- To experimentally characterize the spectral properties of the thermal near-field.
- To investigate nanoscale field localization and energy density enhancements.
Main Methods:
- Utilized scattering scanning near-field optical microscopy (s-SNOM).
- Integrated Fourier-transform spectroscopy with a heated atomic force microscope tip.
- Employed the tip as both a local thermal source and scattering probe in the mid-infrared spectrum.
Main Results:
- Observed spectrally distinct near-field energy densities, orders of magnitude higher than predicted by far-field theories.
- Identified resonant enhancements associated with vibrational, phonon, and phonon-polariton modes.
- Demonstrated nanoscale field localization on and off resonance using model calculations.
Conclusions:
- The experimental characterization of thermal near-fields is now achievable.
- Results provide a foundation for manipulating optical forces and nanoscale radiative heat transfer.
- Developed a novel technique for broadband chemical nanospectroscopy using thermal infrared near-field spectroscopy.
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