Looking at the relative intensities of the signals, I could calculate the elemental concentration of the films and compare it to the molecular stoichiometry. A best-fit procedure allows identifying the contributions from different atomic sites having slightly different binding energies due to variations in the chemical environment. Comparing the film fit results and the molecule stoichiometry, I could conclude that the evaporation occurred without degradation of the diradical. This result is further supported by comparison with the XPS investigations carried out on the powder, i.e., on molecules that did not undergo evaporation. This work shows for the first time that a diradical is stable and robust enough to be evaporated under controlled conditions. I have also monitored the stability of the films in UHV (base pressure 2 x 10 -10 mbar) using XPS, focusing on the N 1s core level spectra that are those of interest in our DFG form 3.06 -01/23 page 4 of 10 work, carrying the information on the radical state. The spectra show no major changes on the time scale investigated, indicating that the diradical is vacuum-stable. Using the same method, I investigated film stability on air exposure. The diradical films show clear changes on the time scale of a few hours. While it is possible to evaporate diradicals and deposit their thin films under controlled conditions without degradation, the results indicate that the diradical films are less stable when compared to their single radical components, .