Design and Optimization of Surface Plasmon Resonance Spectroscopy for Optical Constant Characterization and Potential Sensing Application: Theoretical and Experimental Approaches

Abstract

The best surface plasmon resonance (SPR) signal can be generated based on several factors that include the excitation wavelength, the type of metal used, and the thickness of the metal layer. In this study, the aforementioned factors have been investigated to obtain the best SPR signal. The excitation wavelength of 633 nm and gold metal with thickness of 50 nm were required to generate the SPR signal before the SPR was used for optical constant characterization by fitting of experimental results to the theoretical data. The employed strategy has good agreement with the theoretical value where the real part refractive index, n value, of the gold thin film was 0.1245 while the value for the imaginary part, k, was 3.6812 with 47.7 nm thickness. Besides that, the optical characterization of nanocrystalline cellulose (NCC)-based thin film has also been demonstrated. The n and k values found for this thin film were 1.4240 and 0.2520, respectively, with optimal thickness of 9.5 nm. Interestingly when the NCC-based thin film was exposed to copper ion solution with n value of 1.3333 and k value of 0.0060 to 0.0070 with various concentrations (0.01–10 ppm), a clear change of the refractive index value was observed. This result suggests that the NCC-based thin film has high potential for copper ion sensing using SPR with a sensitivity of 8.0052°/RIU.

Direct and Sensitive Detection of Dopamine Using Carbon Quantum Dots Based Refractive Index Surface Plasmon Resonance Sensor

“…The blue shift can be explained by the changes in the refractive indices and thickness of the sensing medium [ 71 , 72 , 73 , 74 , 75 , 76 ]. To determine the refractive index and the thickness of the Au/CQD thin film, the SPR experimental curves were fitted using a developed fitting program based on Fresnel equations [ 77 , 78 , 79 , 80 , 81 , 82 , 83 ] ( Figure 4 b–h). The obtained refractive index of the gold film was found to be in good agreement with previous studies [ 84 , 85 ], which yielded the n - and k -values of 0.276 and 3.897, respectively, with a thickness of 57.1 nm.…”

Sodium Citrate and Polyvinylpyrrolidone Captured Silver Nanoparticles Transfer to Organic Solvents

“…NPs in the organic phase are colourless due to the change of the dielectric constant of the solvent [23]. NPs in aqueous solution experience changes before and during ultrasonic treatment: ethanol can change the spectrum before sonication since it acts as a reducing agent in the nanoparticles synthesis [24], [25].…”

Plasmonic Nanomaterials for Micro- and Nanoplastics Detection

“…One notable example is the use of SPR in the field of materials science. SPR can be used to study the properties of thin films and coatings [45]. The study of the interactions of SPR with gases [46] and liquids has led to the development of SPR-based sensors for gas detection, environmental monitoring, and food safety [47].…”