  Collinear laser spectroscopy of fast atomic beams has been established as one
of the main tools to perform precision experiments with atoms containing
short-lived nuclei. Although highly sensitive, the spectral resolution of these
techniques is typically limited to several MHz. Here, we study the use of
transient interference phenomena to potentially improve the experimental
resolution. Previous attempts to implement Ramsey-type measurements with fast
beams were limited by the lack of understanding of the observed line shapes. By
using a simple model, we provide a satisfactory description of the previously
observed line shapes, and propose alternative experimental schemes to improve
the resolution in fast ion-beam experiments.
