Radiative lifetime of hydrogenic and quasihydrogenic atoms

Abstract

A universal formula for the upper bound of the radiative lifetime of a hydrogenic level is found to be (3ħ ${}_{}{}^3{}_{}{}^{}$/2m${\alpha }^3$ $Z^4$ $e^4$)$n^3$(l${+(1/2))}^2$. When compared with the exact lifetimes, the expression is found to agree within 10%. For quasihydrogenic atoms and ions, experimental lifetimes are generally found to coincide with the upper bound values.