Barrier layers and methods for forming barrier layers on a porous layer are provided. Each algorithm can produce at least one estimated position with an associated confidence value, and this information from each algorithm can be used to determine a probable location of each pupil. The catalyst comprises in-situ-generated transition metal particles in contact with in-situ-generated refractory particles. A containing force can be created by external electromagnetic fields, ions within the vacuum, or by interactions between the orbiting electrons themselves.