The morphology and self-diffusion in thin films of asymmetric polystyrene-b-2-vinylpyridine (PS-PVP) diblock copolymers were investigated by secondary ion mass spectrometry (SIMS). An oscillatory depth profile of the PVP volume fraction is observed, implying a periodic arrangement of layers of PVP spherical domains organized parallel to the silicon substrate that persisted for films as thick as at least 200 nm (6 layers). The period of the PVP volume fraction oscillation is reasonably close to the (110) spacing of the body centered cubic (bcc) spherical domain structure in the bulk observed by small-angle X-ray scattering (SAXS). Into such films the (self) diffusion of a deuterium-labeled asymmetric diblock copolymer was followed by measuring the SIMS depth profile of H-2(dPS-PVP). The resolution of SIMS is sufficient that the microscopic diffusion involving hopping of dPS-PVP from layer to layer in the microdomain structure can be seen. A very thin 20 nm layer of dPS-PVP was placed on a well-ordered PS-PVP film substrate and heated rapidly to the diffusion temperature. The dPS-PVP molecules diffuse rapidly into the first layer of the PS-PVP,but diffusion into the deeper layers of the PS-PW is much slower. By measuring the H-2 depth profiles, we could determine the dPS-PVP content of each PS-PVP layer and thus a hopping frequency between layers. This hopping frequency could be converted into a diffusion coefficient which compares well to that determined from measurements of diffusion over much longer length scales.