A classical description of subnanometer resolution by atomic features in metallic structures

Recent experiments have evidenced sub-nanometer resolution in plasmonic-enhanced probe spectroscopy. Such a high resolution cannot be simply explained using the commonly considered radii of metallic nanoparticles on plasmonic probes. In this contribution the effects of defects as small as a single atom found on spherical plasmonic particles acting as probing tips are investigated in connection with the spatial resolution provided. The presence of abundant edge and corner sites with atomic scale dimensions in crystalline metallic nanoparticles is evident from transmission electron microscopy (TEM) images. Electrodynamic calculations based on the Finite Element Method (FEM) are implemented to reveal the impact of the presence of such atomic features in probing tips on the lateral spatial resolution and field localization. Our analysis is developed for three different configurations, and under resonant and non-resonant illumination conditions, respectively. Based on this analysis, the limits of field enhancement, lateral resolution and field confinement in plasmon-enhanced spectroscopy and microscopy are inferred, reaching values below 1 nanometer for reasonable atomic sizes

Aqueous Black Colloids of Reticular Nanostructured Gold

Since ancient times, noble gold has continuously contributed to several aspects of life from medicine to electronics. It perpetually reveals its new features. We report the finding of a unique form of gold, reticular nanostructured gold (RNG), as an aqueous black colloid, for which we present a one-step synthesis. The reticules consist of gold crystals that interconnect to form compact strands. RNG exhibits high conductivity and low reflection and these features, coupled with the high specific surface area of the material, could prove valuable for applications in electronics and catalysis. Due to high absorption throughout the visible and infrared domain, RNG has the potential to be applied in the construction of sensitive solar cells or as a substrate for Raman spectroscopy

Rhodium-Complex-Functionalized and Polydopamine-Coated CdSe@CdS Nanorods for Photocatalytic NAD+ Reduction

[Image: see text] We report on a photocatalytic system consisting of CdSe@CdS nanorods coated with a polydopamine (PDA) shell functionalized with molecular rhodium catalysts. The PDA shell was implemented to enhance the photostability of the photosensitizer, to act as a charge-transfer mediator between the nanorods and the catalyst, and to offer multiple options for stable covalent functionalization. This allows for spatial proximity and efficient shuttling of charges between the sensitizer and the reaction center. The activity of the photocatalytic system was demonstrated by light-driven reduction of nicotinamide adenine dinucleotide (NAD(+)) to its reduced form NADH. This work shows that PDA-coated nanostructures present an attractive platform for covalent attachment of reduction and oxidation reaction centers for photocatalytic applications

Changes in the mechanical, structural and electrical properties of glassy carbon due to strontium and silver co-implantation and annealing

Please read abstract in the article.https://www.elsevier.com/locate/apsusc2022-09-22hj2022Physic

Non-martensitic Needle-like Structures on Ni-Ti Alloys - Occurrence and Origin

In the present work the occurrence of needle-like structures that are observed on martensitic and austenitic NiTi after metallographic preparation and etching is described. The investigations show that the needle-like structures form in less than 10s during the etching process if solutions containing HF are applied. The needle-like structures look very similar to martensitic structures. Hence it is tempting to interpret them as martensite. Distinguishing the structures from martensite is not straightforward since standard analysis e.g. by EDX does not yield any differences in chemical composition of the needle-like structures and NiTi. Application of surface sensitive methods like grazing incidence X-ray diffraction clearly shows that the needle-like structures are different from martensitic structures of NiTi. In the present study the options of altering the etching process with the objective of avoiding the formation of the needle-like structures are presented and the origin of the needle-like structures is discussed