This folder contains all raw data underlying the results presented in a manuscript, submitted to J. Phys. Chem. Lett., and entitled: Excitation pulse duration response of upconversion nanoparticles and its applications Authored by: Lucía Labrador-Páez,a Uliana Kostiv,a Qingyun Liu,b Yuanyuan Li,c Hans Ågren,d Jerker Widengren,a and Haichun Liua* a Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden. b Department of Theoretical Chemistry and Biology, KTH Royal Institute of Technology, Stockholm, Sweden. c Wallenberg Wood Science Center, Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden. d Department of Physics and Astronomy, Uppsala University, Uppsala, SE‐75120 Sweden *Corresponding author: E-mail: haichun@kth.se The data files containing raw data and results of the analysis are grouped according to the different figures in the manuscript where the extracted results are presented. ABSTRACT Lanthanide-doped upconversion nanoparticles (UCNPs) have rich photophysics exhibiting complex luminescence kinetics. In this work, we thoroughly investigated the luminescence response of UCNPs to excitation pulse durations. Analysing this response opens new opportunities and advantages in the characterization and application of UCNPs, e.g., for optical encoding/decoding, optical sectioning, in the assignment of transitions to emission peaks, and for improved luminescence nanothermometry. Our work shows that monitoring the UCNP luminescence response to excitation pulse durations using simple and low-cost instrumentation offers a powerful approach to significantly extend the utility of UCNPs.