Characterizing the Nanostructure and Mechanical Behavior of Nanoporous Noble Metals T. John Balk, Department of Chemical and Materials Engineering, University of Kentucky Crack-free thin films of nanoporous Au exhibit an interconnected, porous structure with ligament widths on the order of 10 nm or greater. Nanoscale geometric confinement strongly affects the mechanical behavior. In situ nanoindentation of np-Au reveals dislocation motion within ligaments. Dislocations move easily along ligament axes and tangle in the nodes. When briefly exposed to a focused ion beam, bulk np-Au rapidly cracks at the grain boundaries and undergoes ligament coarsening, illustrating how sensitive this nanoporous material can be. Nanoporous Pd films have pore and ligament sizes of ≈ 5 nm. When exposed to a flowing mixture of H2-N2, np-Pd films exhibit a stress change more quickly than dense Pd films.