Cascade-Induced Alignment Changes of Intensity-Decay Curves

We study the effects of changes of alignment of an atomic level due to cascading as a function of time after excitation. For many of the decays observed in beam-foil spectroscopy, we expect the cascade-induced alignment to be close to zero. Accordingly, we have found that the difference between multiexponential decay curves measured in light polarized parallel and perpendicular to the beam may contain only a single exponential characteristic of the level lifetime, thus providing a cascade-free lifetime measurement. By similar considerations, we have also used alignment information to reduce or eliminate unresolved blending in lifetime measurements.