This data set contains all data underlying the figures in the main text and supporting information. The information on how the data was acquired and processed is detailed in the open access manuscript + SI which has been deposited in this repository and is also available open-access via the publisher Nature Communications under the title "Extracting Quantitative Dielectric Properties from Pump-Probe Spectroscopy". All the extracted data can also be generated from the experimental data by running the codes on the GitHub repository, the link to which is available in the Main text.

Main Figures: Figure 1 - Differential transmission slices of the data presented in Figure 3 along with explicit data slices of the transient dielectric function also presented in Figure 3. Figure 2 - a) Differential transmission map of CsPbBr3 which when run through our analysis code (available on GitHub) produces the 'transient dielectric function' plotted in b) along with unnormalised slices of the differential transmission map, c) Computed transient reflectivity and dielectric function slices and d) Slices of the real refractive index and measure Frequency Domain Interferometry data Figure 3 - Same as Figure 2 but on Pentacene. Figure 4 - a) Differential reflectivity map of GaAs wafer and the extracted transient imaginary dielectric function (b).

All analysis was performed using Python, the interactive Jupyter notebooks are available in the GitHub repository linked in the paper.