Two-dimensional collective pinning in sputtered amorphous films is a useful tool to study defects on the scale of the coherence length (∼7nm). In the asdeposited samples pinning was predominantly caused by quasi-dislocation loops. A change in the pinning characteristics was observed in some special cases: after annealing of the most inhomogeneous sample (thickness 3μm) at 580°C for 26h, and after doping of an annealed sample (thickness 0.5μm) with 0.2 at.% hydrogen. X-ray scattering experiments did not reveal any onset of recrystallization. The effects are discussed in terms of a second, relatively weak particle pin mechanism correlated with the stronger pins. © 1984.