Fundamental Concerns of Optical Fluorescence Intensity Ratio-Based Thermometry

Abstract

This chapter provides a comprehensive exploration of optical fluorescence intensity ratio (FIR) temperature sensing, blending theoretical underpinnings with practical applications. It underscores the intrinsic sensitivity and non-invasiveness of FIR technology, spanning diverse scientific disciplines where its utility is paramount. Central to the discussion are the intricate energy transfer mechanisms within fluorescence emissions from temperature-sensitive materials, revealing their nuanced responses to thermal changes. Fundamental to FIR thermometry are the lanthanide (Ln3+) ions, which play pivotal roles due to their unique electronic configurations. These elements exhibit temperature-dependent variations in fluorescence properties, including intensity and lifetime, crucial for accurate temperature determination. Specifically, the chapter delves into the utilization of erbium (Er3+) and holmium (Ho3+) ions in the context of FIR thermometry, highlighting their distinct contributions to enhancing temperature sensitivity. The Er3+/Ho3+ co-doped nano-garnet emerges as a promising material in this field, effectively bridging theoretical frameworks with practical implementations. The narrative is enriched by the incorporation of the Boltzmann distribution equation, which provides a robust theoretical foundation for understanding temperature-dependent fluorescence phenomena exhibited by Ln3+ ions. This chapter serves as a valuable resource, offering a concise understanding on the forefront of optical FIR-based thermometry for researchers and professionals alike.