A high sensitivity optical thermometry on the basis of the intensity ratio between the fluorescence and phosphorescence in lutecium porphyrin.

An optical thermometry was performed utilizing the intensity ratio between the fluorescence and the phosphorescence of lutecium hematoporphyrin (Lu-HMME). In spite of the large energy level difference between the singlet first excited state (S 1) and the triple first excited state (T 1), the emission intensities of the two channels were on the same order of magnitude, and the resulted luminescence intensity ratio was confirmed to follow the Boltzmann distribution law. The huge difference in population was made up by the intrinsic properties of Lu-HMME that the transition probability of the S 1 state is several orders of magnitude higher than that of T 1. Based on this, Lu-HMME is a candidate for optical high-temperature sensors with high relative sensitivity and good temperature resolution. [Display omitted] • Lu-HMME thermometry was based on the intensity ratio between fluorescence and phosphorescence. • The singlet first excited state and triple first excited state was regarded as the TCLs. • A high relative sensitivity was shown with 2.49% K−1 at 288 K. • An excellent photostability was performed and the temperature resolution could reach 0.07 K at 308 K. [ABSTRACT FROM AUTHOR]