Desorption or disordering from diffraction peak intensity decay?

When an ordered overlayer is heated at a high enough temperature, there is loss of order that can be monitored through the decay of the peak intensity of diffraction spots. This is caused by either particle loss to the gas phase or the onset of diffusion that disorders the overlayer. With the use of model simulations on a c(2 × 2) ordered overlayer, we show how the peak intensity decay can differentiate between the two cases. We further examine the growth laws describing the growth of disorder to see if they obey similar laws as the reverse ordering processes. When no interfaces separating degenerate phases are present, disordering and ordering processes do not obey the same growth laws.