3D hotspot matrix of Au nanoparticles on Au island film with a spacer layer of dithiol molecules for highly sensitive surface-enhanced Raman spectroscopy

Engineering of efficient plasmonic hotspots has been receiving great attention to enhance the sensitivity of surface-enhanced Raman scattering (SERS). In the present study, we propose a highly sensitive SERS platform based on Au nanoparticles (AuNPs) on Au island film (AuIF) with a spacer layer of 1,4-benzenedimethanethiol (BDMT). The three-dimensional (3D) hotspot matrix has been rationally designed based on the idea of employing 3D hotspots with a vertical nanogap between AuIF and AuNPs after generating large area two-dimensional hotspots of AuIF. AuNPs@BDMT@AuIF are fabricated by functionalizing BDMT on AuIF and then immobilizing AuNPs. The SERS performance is investigated with Rhodamine 6G as a probe molecule and the determined enhancement factor is 1.3 × 105. The AuNPs@BDMT@AuIF are then employed to detect thiram, which is used as a fungicide, with a detection limit of 13 nM. Our proposed platform thus shows significant potential for use in highly sensitive SERS sensors.

Terahertz Photoconductive Antenna Based on a Topological Insulator Nanofilm

In this study, the efficient generation of terahertz radiation by a dipole photoconductive antenna, based on a thin island film of a topological insulator, was experimentally demonstrated. The performance of the Bi1.9Sb0.1Te2Se antenna was shown to be no worse than those of a semiconductor photoconductive antenna, which is an order of magnitude thicker. The current–voltage characteristics were studied for the photo and dark currents in Bi1.9Sb0.1Te2Se. The possible mechanisms for generating terahertz waves were analyzed by comparing the characteristics of terahertz radiation of an electrically biased and unbiased topological insulator.

Plasmonic enhancement of photocurrent generation in a photosystem I-based hybrid electrode

We demonstrate that oriented assembly of red algal photosystem I reaction centers on a plasmonically active Silver Island Film leads to strong enhancement of both photocurrent and fluorescence intensity.