The file names indicate to which figure the data belongs, e.g:

figure_1b_90K_data contains two columns of (photon energy, intensity) pairs for the trace of Figure 1b recorded at a temperature of 90K

figure_3b_all_fields contains columns of all the data shown in Figure 3, where the first column contains the photon energies and the other columns contain the intensities recorded at the magnetic fields specified in the column headers (top row of the data).