Thin Functional Zeolite Layer Supported on Infrared Resonant Nano-Antennas for the Detection of Benzene Traces

Infrared absorption spectroscopy is a powerful analytical tool that enables the identification of molecular species. The sensitivity of this technique, that is strongly limited by the small absorption cross-section of molecular vibration, can be greatly improved by resonant interaction with nano-antennas via the surface-enhanced infrared absorption (SEIRA) mechanism. However, most of the examples of SEIRA concern solid-state molecular layers adsorbed on the nano-antennas, while the detection of gas traces still remains elusive due to the spatial extent of the near-field that is used to amplify the molecular vibrations resonantly. Here, a hybrid system composed of a plasmonic nano-antenna array coupled with nanosized zeolite coating for detection of volatile organic compounds in the near field of the resonators is demonstrated. The concerted action of the coating and the nano-antennas enabled the authors to detect record traces of benzene (25 ppb) within 10 min. This approach may ultimately allow the fabrication of a compact system for rapid detection of pharmaceutical and biocompounds with high sensitivity and high selectivity.