This resulted in short-range repulsion acting at larger distances than water, which was visible in histograms in Figure and explained the shift of the isotherms. At the same time, the minimum of the long-range attraction seemed to be deeper than at the water subphase, as "icefloe" like aggregates were visible under BAM (Figure ) directly after the deposition of the film at the air/water interface. However, although we depicted the interactions according to DLVO theory, we postulated that other forces not described by this theory were crucial in our system. According to DLVO theory, adding ions should screen the interactions and shift the interaction potential curve towards smaller distances, unlike in our experiments. Bresme et al. listed five main interactions to be considered in liquid-surface deposited nanoparticles: