Über einige Probleme bei instabilen quantenmechanischen Systemen

If an exponential decay law is measured (which clearly need not be found in every case) it cannot be concluded that the line shape must be lorentzian. To show that the possible energy spectra may differ from a Lorentz shape by a well measurable amount an example of such a spectrum is constructed, leading to an exponential decay law in an even better approximation than a lorentzian spectrum. Hereafter various facts about decaying systems are discussed in connection with scattering theory. Finally it is shown that ordinary Mößbauer experiments are not suited for line shape measurements and modified experiments are proposed.