Determination of scaling exponents in Ag(100) homoepitaxy with x-ray diffraction profiles

Homoepitaxy of Ag(100) at different temperatures has been studied by collecting the angular distribution of the intensities of $x$ rays diffracted from the growing film, in real time without interruption of the growth at relatively high growth rates (one atomic layer every 80 seconds). The temporal evolution of the long- and medium-range surface correlations has been used to determine the coarsening and roughening exponents at different temperatures. A simple phenomenological model based on rate equations has been found accurately to fit the data. The results suggest that the energy barrier to descend steps is small.