A Novel Route for a Fluorescent Temperature Sensor Based on the Reabsorption Process in Sm2+‐Doped KCl

Abstract

Fluorescent temperature sensors have attracted attention in recent years, due to their potential for use in situations where conventional temperature sensors are unsuitable. There are a lack of appropriate sensors at the microscale for industrial, laboratory, and medical applications. Sm2+:KCl crystals possess luminescence properties that enable them to be used as sensors in a new approach for local temperature measurements, by determining the blueshift or the ratio between the intensities from the allowed 4f–5d transitions. A broad emission band centered at 750 nm at 300 K, with high quantum yield (1.00 ± 0.05), is observed when exciting these crystals in the ultraviolet (UV)–vis range. This emission lies within the optical response range of commercial Si‐based photodetectors, which are readily available at relatively low costs. Furthermore, the crystals can be excited using red light‐emitting diodes (LEDs) or a solid‐state laser at 600–650 nm, which are used to produce fluorescent thermometers with a relative sensitivity of 0.24% K−1 (A1/A2 ratio) at 299 K and 1.43 cm−1 K−1 (blueshift).