Notes on thermometric artefacts by Er3+ luminescence band interference

Abstract

Optical thermometry based on the intensity ratio of the H-2(11/2) -> I-4(15/2) (525 nm) and S-4(3/2) -> I-4(15/2) (545 nm) emission of Er3+ provides a powerful tool for microscale temperature sensing. Crystalline beta-NaYF4:Er,Yb is an excellent thermometry material for green upconversion emission upon NIR laser excitation. However, interfering H-2(9/2) -> I-4(13/2) emission is observed around 555 nm for continuous-wave laser excitation intensities above 10 W/cm(2). In this study, the green Er3+ emission bands are characterized and it is demonstrated how the true sample temperature is determined circumventing possible artefacts.