Size-Dependent RIS and FOM of Ag-Fe and Au-Fe Bimetallic Alloys in Triangular Prism: a DDA Study

Pradeep Bhatia,M M Sinha,S S Verma

doi:10.1007/s13320-019-0547-8

Pradeep Bhatia, M M Sinha + Show 1 more

Open Access

https://doi.org/10.1007/s13320-019-0547-8

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Abstract

In this paper, the localized surface plasmon resonance (LSPR) peak of Ag-Fe and Au-Fe alloy nanoparticles for the triangular prism is calculated by using the discrete dipole approximation (DDA) method. We investigate the variation of the resonance wavelength, refractive index sensitivity, and figure of merit with the particles size and alloy compositions. We perform a comparative study on the refractive index sensitivity and figure of merit of alloys in order to find the considered (Ag-Fe and Au-Fe) alloys with high sensitivity. The refractive index sensitivity of the Au-Fe alloy is found higher than that of the Ag-Fe alloy. Therefore, to optimize the size of alloy nanoparticles (NPs) for the triangular prism, the figure of merit is calculated and observed that the optimized size is 50nm and 20 nm for Ag-Fe and Au-Fe alloys, respectively. A comparison of Ag-Fe shows that the Au-Fe alloy NPs have greater figure of merit (FOM) and thus may be more suitable for applications in biosensing.

Highlights

The current status of research takes account of the combination of magnetism with plasmonic materials or nanoparticles (NPs) towards catalysis, biosensing, and drug delivery applications
The optical properties such as absorption efficiencies of Ag-Fe alloys nanoparticles are simulated by using the discrete dipole approximation (DDA) method
Au-Fe alloy multipolar peaks appear for all considered particle sizes, and localized surface plasmon resonance (LSPR) peaks shift towards the longer wavelength with an increase in the size

Summary

Introduction

The current status of research takes account of the combination of magnetism with plasmonic materials or nanoparticles (NPs) towards catalysis, biosensing, and drug delivery applications. LSPR spectra can be improved by adjusting the refractive index of the environment All of these factors motivate researchers to investigate the primary optical properties such as extinction, absorption, and scattering of bimetallic alloy nanoparticles of varying shapes and sizes in different surrounding media. The preliminary interesting optical properties shown by the Au-Fe triangular prism and reported in [23] have motivated us to study further the mechanism of LSPR for sensing of magneto-plasmonics NPs of iron alloys with Au and Ag. we have calculated the refractive index sensitivity (RIS) and figure of merit (FOM) of Ag-Fe and Au-Fe alloy nanoparticles and made a comparison of two considered bimetallic systems

Computational method

Results and discussion

Conclusions