CONICET | Buscador de Institutos y Recursos Humanos

Noble metal-based Photonic Crystals (PCs) have emerged as outstanding candidates for precise light management, projecting applications in strategic areas for society like high-sensitivity and fast molecular (inorganic/organic/bio) sensing by Surface-Enhanced Raman Spectroscopy (SERS). In this work, we report a brief but exhaustive study on the gross potential of large-scale Au nanodisks-based 2D PCs fabricated by Interference Laser Lithography (ILL) for efficient SERS-based molecular sensing. This technique was used to fabricate periodic nanoarrays (period of 470 [nm]) of Au nanodisks with thicknesses from 50 up to 125 [nm]. The period was chosen following FDTD simulations that suggest the best electric-near field enhancement for this condition. Confocal Raman microscopy and methylene blue (as Raman marker) were used to assess the samples´ performance for molecular sensing using 633 and 780 [nm] laser sources. SERS studies show the nanodisks´ thicknesses are a relevant tunning factor for the Raman signal amplification, observing higher signal enhancements for higher thicknesses. Results show the best performance for 633 [nm]-laser, which enables measuring the characteristic Raman footprint with good spectral resolution using relatively low powers (0.04 1 [mW]) and acquisition times (1 30 [s]). The observed thickness and excitation wavelength effects on the Raman signal enhancement wereconsistent with FDTD simulations, which predict higher electric-near field amplifications for higher thickness and shorter wavelengths within the red/near-infrared range. This research demonstrates the potential of our PCs fabricated using an efficient large-scale and low-cost lithography technique, concerning ion or electron beambased ones, for fast and high spectral resolution SERS-based molecular sensing.Keywords: Molecular Sensing, Surface-Enhanced Raman Spectroscopy, 2D Photonic Crystals, Interference Laser Lithograph

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