Substrate enhanced infrared nanospectroscopy of molecular vibrations

CIC nanoGUNE Seminars

Lars Mester
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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Substrate enhanced infrared nanospectroscopy of molecular vibrations S-SNOM and nano-FTIR spectroscopy allow for label-free mapping and chemical identification of organic and inorganic materials with nanoscale spatial resolution. However, the detection of thin molecular layers and nanostructures on standard substrates is still challenged by weak signals. Here, we demonstrate a significant enhancement of nano-FTIR signals of a thin organic layer by exploiting polariton-resonant tip-substrate coupling and surface polariton illumination of the probing tip. We achieve up to nearly one order of magnitude signal enhancement on a phonon-polaritonic quartz (c-SiO2) substrate, as compared to nano-FTIR spectra obtained on metal (Au) substrates, and up to two orders of magnitude when compared to the standard infrared spectroscopy substrate CaF2. Our results will be of critical importance for boosting nano-FTIR spectroscopy towards the routine detection of monolayers and single molecules.