Highly sensitive bimetallic plasmonic sensing probe for aqueous samples

摘要

In spite of having very large real part of permittivity, Rhodium (Rh) is rarely used as a plasmonic metal in surface plasmon resonance (SPR) based sensing applications. Here, we theoretically present a simple SPR based prism-coupled refractive index sensor in Kretschmann geometry utilizing a bimetallic layer of Rhodium (Rh) and Silver (Ag) as plasmonic metal layer on the base of the SF10 glass prism. In addition Silicon is used as an upper most layer, which not only protects the oxidation-prone Ag film but also enhances the field and thereby the sensor's performance. Each of the layers is optimized for maximum sensitivity in the visible region at 632 nm wavelength of excitation. The sensor exhibits an extremely high sensitivity of 229 degree/refractive index unit (RIU) for analyte refractive indices (RIs) varying from 1.33 to 1.37 RIU.