Characterization method for relative Raman enhancement for surface-enhanced Raman spectroscopy using gold nanoparticle dimer array

Abstract

In this paper, a characterization method for Raman enhancement for highly sensitive and quantitative surface-enhanced Raman spectroscopy (SERS) is reported. A particle dimer shows a marked electromagnetic enhancement when the particle connection direction is matched to the polarization direction of incident light. In this study, dimers were arrayed by nanotrench-guided self-assembly for a marked total Raman enhancement. By measuring acetonedicarboxylic acid, the fabricated structures were characterized for SERS depending on the polarization angle against the particle connection direction. This indicates that the fabricated structures cause an effective SERS enhancement, which is dominated by the electromagnetic enhancement. Then, we measured 4,4'-bipyridine, which is a pesticide material, for quantitative analysis. In advance, we evaluated the enhancement of the particle structure by the Raman measurement of acetonedicarboxylic acid. Finally, we compared the Raman intensities of acetonedicarboxylic acid and 4,4'-bipyridine. Their intensities showed good correlation. The advantage of this method for previously evaluating the enhancement of the substrate was demonstrated. This developed SERS characterization method is expected to be applied to various quantitative trace analyses of molecules with high sensitivity.

Chemical sensing with Au and Ag nanoparticles

“…The LSPR shift induced by local changes in the refractive index or by coupling between particles above discussed are the simplest and more immediate approaches to exploit metal nanoparticles as active materials or transducers in chemical sensing but the evanescent near field surrounding metal nanoparticles can be also exploited to strongly amplify the optical signals (including, fluorescence, IR absorption, and Raman) of molecules which are located in close proximity to the particle's surface. These techniques, called Surface-Enhanced Fluorescence (SEF), (322,323) IR absorption (SEIRA) (324) and Raman spectroscopy (SERS),( 325) have shown great potential in the field of sensing and, in particular, SERS can allow increased sensitivity up to singlemolecule detection (326,327) but their working principles and their detailed description are far beyond the scope of this review.…”

Surface‐enhanced Raman spectroscopy with gold nanoparticle dimers created by sacrificial DNA origami technique

“…However, creating metal nanostructures with nanogaps from thin metal film using a lift‐off process is not easy due to the resolution limit of electron beam lithography and the difficulty of controlling crystal growth of metal nanostructures [6–8]. An alternative method using gold nanoparticles (AuNPs) synthesised in solution with a controlled size and arranged on a substrate has thus been developed [1–3, 9, 10]. In this method, two AuNPs covered by a citrate molecular layer for stabilisation in solution are trapped in a nanometre‐scale groove created using a nanofabrication technique such as electron beam lithography.…”

“…1. Introduction: Surface-enhanced Raman spectroscopy (SERS) is a practical analysis method for detecting and identifying molecules dissolved in water at low concentration [1][2][3]. It is thus attracting interest in various fields, including medicine, biology, and environmental monitoring.…”

Optical characteristics of nanospace of silver nanowire on a silver mirror

“…However, since such particles simultaneously form aggregates and dimers, it is very difficult to arrange the particles side by side with high probability and to control the space. Solutions to this problem include chemically modifying the particle surface, and implementing spatial control using a high precision physical processing method and a formation method thereof …”

“…Recently approaches combine these methods. For example, an uneven template and gel substrate have been combined with a self‐organizing method to realize the fabrication and control of narrow gaps. Moreover, Raman sensing of target particles using the method has been realized.…”