Experimental verification of field-enhanced molecular vibrational scattering at single infrared antennas
arXiv:2401.09104 · doi:10.1038/s41467-024-50869-x
Abstract
Surface-enhanced infrared absorption (SEIRA) spectroscopy exploits the field enhancement near nanophotonic structures for highly sensitive characterization of (bio)molecules. The vibrational signature observed in SEIRA spectra is typically interpreted as field-enhanced molecular absorption. Here we study molecular vibrations in the near field of single antennas and show that the vibrational signature can be equally well explained by field-enhanced molecular scattering. Although the infrared scattering cross section of molecules is negligible compared to their absorption cross section, the interference between the molecular-scattered field and the incident field enhances the spectral signature caused by molecular vibrational scattering by 10 orders of magnitude, thus becoming as large as that of field-enhanced molecular absorption. We provide experimental evidence that field-enhanced molecular scattering can be measured, scales in intensity with the fourth power of the local field enhancement and fully explains the vibrational signature in SEIRA spectra in both magnitude and line shape. Our work may open new paths for developing highly sensitive SEIRA sensors that exploit the presented scattering concept.
arXiv comment38 pages, 5 figures, 6 extended data figures
References in corpus (5)
- Mid-Infrared Plasmonic Biosensing with Graphene
- Boron nitride nanoresonators for phonon-enhanced molecular vibrational spectroscopy at the strong coupling limit
- Ab initio theory of Fano resonances in plasmonic nanostructures and metamaterials
- Amplitude- and phase-resolved nano-imaging and nano-spectroscopy of polaritons in liquid environment
- High-resolution label-free imaging of tissue morphology with confocal phase microscopy