Scaling of the hysteresis loop in two-dimensional solidification

The first-order phase transitions between a two-dimensional (2d) gas and th e 2d solid of the first monolayer have been studied for the noble gases Ar, Kr and Xe on a NaCl(100) surface in quasi-equilibrium with the three-dimen sional (3d) gas phase. Using linear temperature ramps, we show that the wid ths of the hysteresis loops of these transitions as a function of the heati ng rate, r, scale with a power law proportional to r(alpha), with ct betwee n 0.4 and 0.5 depending on the system. The hysteresis loops for different h eating rates are similar. The island area of the condensed layer was found to grow initially with a t(4) time dependence. These results are in agreeme nt with theory, which predicts alpha = 0.5 and hysteresis loop similarity.