On the exponential decay of eigenfunctions to Schroedinger-type operators

This talk is concerned with the asymptotic behaviour of eigenfunctions related to the Schroedinger problem or the Helmholtz equation. After illuminating the physical background, basic properties of the eigenfunctions are derived. The main result is an exponential decay estimate for perturbations of the eigenfunctions caused by a local potential. A one-dimensional example illustrates typical properties of the eigenfunctions as well as limits of the theory.