Large dynamic range SPR measurements in the visible using a ZnSe prism

TL;DR

This paper demonstrates large dynamic range SPR measurements in the visible spectrum using a ZnSe prism, enabling broader solvent compatibility and potential extension into the mid-infrared.

Contribution

The study introduces a ZnSe prism-based SPR technique that overcomes angular limitations of borosilicate systems, allowing measurements across a wider range of solvents and extending into mid-infrared.

Findings

Achieved index measurement range from 1 to 1.7.

Measured refractive index change for glucose in water.

Estimated angular resolution uncertainty between 1.5 and 6 degrees.

Abstract

Large dynamic index measurement range (n = 1 to n = 1.7) using surface plasmon resonance (SPR) shifts is demonstrated with a ZnSe prism at 632.8 nm, limited by the available high index liquid hosts. In contrast to borosilicate based SPR measurements where angular limitations restrict solvent use to water and requires considerable care dealing with Fresnel reflections, the ZnSe approach allows SPR spectroscopies to be applied to a varied range of solvents An uncertainty in angular resolution between 1.5 and 6 deg, depending on the solvent and SPR angle, was estimated. The refractive index change for a given glucose concentration in water was measured to be n = (0.114 to 0.007) per precentage C6H12O6 conc. Given the transmission properties of ZnSe the processes can be readily extended into the mid infrared.