Enhanced optical cross-section of radiation induced defect centers under plasmon resonance conditions: Shifting stimulation wavelength of optically stimulated luminescence dosimeters

Abstract

Plasmon-enhanced luminescence is an important tool for development of advanced sensing technologies but the mechanisms originating these enhancements are still in debate. In this work, we investigate plasmon-enhanced luminescence mechanisms using the Optically Stimulated Luminescence (OSL) from defect centers in X-ray irradiated sodium chloride nanocrystals deposited on silver nanoparticle (AgNP) films with varying plasmon properties upon blue, green, and red OSL stimulation. Although the absolute OSL intensity for NaCl crystals is higher upon blue stimulation, under plasmon resonance conditions, higher absolute OSL intensity occurs upon green stimulation and the largest OSL enhancements are observed by employing red stimulation. These results suggest that, as long as the OSL stimulation wavelength is well tuned with the film plasmon band, plasmonic coupling does not depend on the trap depth and that the largest luminescence enhancements are achieved in spectral regions where the optical cross-sections of the defect centers are smaller. In terms of radiation dosimetry applications, this result allows to shift the stimulation wavelength farther from the OSL emission window, improving the signal to noise ratio and the dose assessment sensitivity and accuracy.