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Surface-enhanced Raman spectroscopy (SERS) has shown a strong Raman enhancement with bimetallic nanoparticles. The combination of the different bimetallic nanoparticles is used in the field of SERS sensors. These sensors can resonate with the organic molecules adsorbed on their surfaces for SERS enhancement. Fabricating these bimetallic, cost-effective and ultrasensitive SERS sensors is a great challenge. To overcome this challenge, a rapid fabrication method of ultrasensitive noble SERS sensors that enable sub-femtomolar detection of molecular analytes, is reported here. SERS sensor is obtained by application of the silver nanorods (AgNRs) deposited on copper nanoflowers (CuNFs) fabricated by chemical reduction and chemical etching, respectively. Purity and structural characteristics of the SERS sensor are measured qualitatively by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared microscopy and Raman analysis. Rhodamine 6 g as an analyte analyses the sensitivity of the SERS sensor. The detection limit and enhancement factor are found to be 10−13 M and 109 respectively for AgNRs deposited CuNFs etched for 30 min. This study reveals that the AgNRs deposited CuNFs are practically found to be sensitive SERS sensors. [ABSTRACT FROM AUTHOR]

This experimental study's main goal is to investigate the impact of various silver concentrations on the optical characteristics of Agshell/Aucore bimetallic nanoparticles. By using the pulsed laser ablation in liquid (PLAL) technique on the gold target at the bottom of the container full of silver colloids, the silver/gold nanoparticles are ablated. Colloidal silver nanoparticles, created through a chemical reduction process, are inside the container. The second harmonic of the pulsed Nd:YAG laser is used to irradiate the colloidal mixture of mixed nanoparticles at a wavelength of 532 nm. The Agshell/Aucore bimetallic nanoparticles are created by transferring laser energy to gold nanoparticles, which have a peak absorption of around 530 nm. The experimental variables are the volumetric ratio of nanoparticle solutions. X-ray diffraction pattern (XRD), spectroscopy in the UV–Vis-NIR and IR ranges, dynamic light scattering (DLS), energy-dispersive spectroscopy (EDS), photoluminescence spectrum (PL), and Fourier transform infrared spectroscopy (FT-IR) are used to identify bimetallic nanoparticles. Additionally, FE-SEM and TEM pictures are used to look at the size and morphology of nanoparticles. In order to test the reactivity of silver nanoparticles in the bimetallic system, one goal of this research is the production of stable bimetallic systems and the examination of optical properties. Additionally, a bimetallic structure with a variable silver concentration's shell thickness and catalytic qualities is examined. All samples in the visible range have dipole absorption observable. On the other hand, the first sample with a lower silver concentration exhibits quadrupole absorption. [ABSTRACT FROM AUTHOR]