Lifting of nodes by disorder in extended-s-state superconductors: Application to ferropnictides

We show, using a simple model, how ordinary disorder can gap an extended-s- (A(1g)) symmetry superconducting state with nodes. The concomitant crossover of thermodynamic properties, particularly the T dependence of the superfluid density, from pure power-law behavior to an activated one is exhibited. We discuss applications of this scenario to experiments on the ferropnictide superconductors.