Large-area cost-effective lithography-free infrared metasurface absorbers for molecular detection

The implementation of metasurface absorbers for advanced sensing applications in the infrared spectral range is gaining prominence. Nevertheless, scale-up is challenging because their subwavelength features require complex fabrication techniques. Here, we present centimeter-sized nanostructured metasurface absorbers, prepared using the nanoporous anodic aluminum oxide template method, which exhibit a high and polarization-insensitive absorptivity at near-infrared wavelengths. Their sensing potential as surface-enhanced Raman spectroscopy substrates is demonstrated by analyzing Raman spectra of methyl parathion pesticides at concentrations as low as 100 ppb. Our results offer a stable, cost-effective, scalable, and uniform solution for metasurface-based molecular detection applications with a high sensitivity.status: publishe

Morphology, optical, and electric properties of polymerquantum dots nanocomposites: effect of polymeric matrix

Polymer-CdTe quantum dots (QDs) nanocomposites were developed via solvent casting. Colloidal CdTe QDs, synthesized in aqueous solution, were transferred to organic media by exchanging of the original capping ligands by a long-chain thiol. Different commercial polymers (PMMA, OPS, PS, and PC), transparent in the visible spectral range, were chosen as matrices. Stock solutions of the polymers were prepared in suitable concentration (2 wt%) for the production of thin films with good quality, able to maximize the solubility of QDs, without phase separation. Studies on the morphological and optical properties were performed. The results showed that the polymer matrix has a considerable effect on QDs' morphology, size, and electric conductivity. PMMA demonstrated to be the most promising embedding matrix, offering new possibilities for optoelectronic applications of polymer-QD nanocomposites.The authors acknowledge the n-STeP-Nanostructured systems for Tailored Performance, with reference NORTE-07-0124-FEDER-000039, supported by the Programa Operacional Regional do Norte (ON.2), PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25-2013-2014). The authors also acknowledge Agnieszka Tercjak from Dpto. Ingenieria Quimica y del Medio Ambiente, Escuela Politecnica Donostia-San Sebastian for the AFM measurements.info:eu-repo/semantics/publishedVersio