LiYF4:Er3+ for near-infrared luminescent cryothermometry

Abstract

We explore the possibility of using the luminescence of LiYF4:Er3+ to measure cryogenic temperatures. Temperature dependences (2.5 K → 190 K) of the luminescence intensity ratios and linewidths are studied in the regions of infrared transitions 4I13/2 → 4I15/2 (∼1.5 μm) and 4I11/2 → 4I15/2 (∼0.98 μm) using high-resolution Fourier spectroscopy. Pairs of spectral lines 6550–6510 cm−1, 10176–10161 cm−1, and 6482–6478 cm−1 can be used for ratiometric Boltzmann thermometry with maximum absolute sensitivity at temperatures of 28.8, 10.8, and 2.9 K, respectively, and corresponding relative sensitivities of 6.9, 18.5, and 70% K−1 at these temperatures. The temperature dependence of the linewidth of 6510 cm−1 line is favorable for measuring higher temperatures.