Step Dynamics Measurements with Time-Resolved Low Energy Electron Diffraction Andreas Menzel School of Physics, Georgia Tech Step dynamics have been an important research field because of their relation to both equilibrium crystal structures and to crystal growth. However, near-equilibrium surface kinetics measurements capable of covering wide temperature- (i.e. time-) regimes and large length scales are sparse. To measure step fluctuations we propose using time-resolved low energy electron diffraction (LEED). We call this new experimental technique temporal LEED spectroscopy (TLS). It is based on measuring the autocorrelation of the fluctuations of the diffraction intensity to infer microscopic processes on the scattering surface. Existing theoretical models successfully cast step fluctuations and the underlying diffusion processes in Langevin-equations. Based on these models one can determine which functional forms of autocorrelation to expect from the experiment and quantitatively interpret measured TLS signals. TLS is demonstrated with data from vicinal Si(001) and compared with Ostwald ripening studies and low energy electron microscopy (LEEM) measurements. Differences in the interpretation of results from different temperature regimes and different experimental techniques can be reconciled, suggesting dynamics on Si(001) that are quite complex.