Measurement of persistence in 1D diffusion

Using a novel NMR scheme we observed persistence in 1D gas diffusion. Analy tical approximations and numerical simulations have indicated that for an i nitially random array of spins undergoing diffusion, the probability p(t) t hat the average spin magnetization in a given region has not changed sign ( i.e., "persists") up to time t follows a power law t(-theta), where theta, depends on the dimensionality of the system. Using laser-polarized Xe-129 g as, we prepared an initial "quasirandom" 1D array of spin magnetization and then monitored the ensemble's evolution due to diffusion using real-time N MR imaging. Our measurements are consistent with analytical and numerical p redictions of theta approximate to 0.12.