Atomic Structure and 3D Shape of a Multibranched Plasmonic Nanostar from a Single Spatially Resolved Electron Diffraction Map.

Despite the interest in improving the sensitivity of optical sensors using plasmonic nanoparticles (NPs) (rods, wires, and stars), the full structural characterization of complex shape nanostructures is challenging. Here, we derive from a single scanning transmission electron microscope diffraction map (4D-STEM) a detailed determination of both the 3D shape and atomic arrangement of an individual 6-branched AuAg nanostar (NS) with high-aspect-ratio legs. The NS core displays an icosahedral structure, and legs are decahedral rods attached along the 5-fold axes at the core apexes.

The problem of conserving an ecosystem that has not been completely delineated and mapped: the case of the Cocais Palm Forest.

Land cover changes threaten biodiversity and alter the geographic distribution of forests worldwide. Studies on this topic are important to establish conservation strategies and public policies. However, different studies may propose different spatial representations due to differences when identifying, classifying, and/or mapping the same vegetation formation, as observed for the Cocais Forest region.

Surface-enhanced Raman spectroscopy of one and a few molecules of acid 4-mercaptobenzoic in AgNP enabled by hot spots generated by hydrogen bonding.

The present study reports a direct approach to generate efficient hot spots using a nonresonant molecule bound to the inner part or hot spots that can increase the SERS sensitivity to obtain spectra of one and a few molecules. The 4-Mercaptobenzoic acid (4-MBA) adsorbate, connected to the Ag surface by a thiolate-Ag bonding, was able to trigger a self-assembly process of AgNP, which occurred by cooperative hydrogen bonds between the carboxylic groups of 4-MBA located in different nanoparticles when the pH was adjusted to 4. The self-assembly structure was characterized by UV-Vis spectroscopy and SERS (Surface Enhancement Raman Scattering), and DFT-based calculation of the model complex [AgNP-(4-MBA)-AgNP] was employed to improve the understanding of the self-assembled complex formation through the comparison of calculated and experimental SERS spectra.

Structural characterization and plasmonic properties of manganese oxide-coated gold nanorods.

The preparation of metal@(dielectric or semiconductor) core@shell hybrid materials have been shown promising for both SERS and SEF applications due to improved stability in the presence of ions and the adsorbate compared to non-covered metallic nanoparticles. However, fine control over the thickness of the covering layer is essential to maximize the intrinsic trade-off between the plasmonic enhancement and the chemical stability improvement. Here, the preparation of manganese dioxide ultrathin layers covered gold nanorods (AuNR@MnO) with varying thicknesses of the MnO layer is reported, and the characterization and evaluation of the resulting materials as SERS and SEF substrate.