Dynamics of the surface phase transformations in the K/Al(111) system

Second harmonic generation has been used to study the dynamics of the phase transformations which occur for submonolayer films of potassium on the (111) face of aluminum. The second harmonic signal is very sensitive to the geometrical structure, symmetry, and electronic structure of the adsorbed layer. This system reveals an intricate phase diagram including two-dimensional condensation, co-existence regimes between a lattice gas and ordered islands, and order-preserving irreversible transformation. The latter transformation which occurs as a function of temperature shows a damped-oscillatory behavior.