Quantum beat spectroscopy of jet-cooled transient radicals generated by a pulsed electrical discharge

Using a pulsed electrical discharge nozzle, we have extended quantum beat spectroscopy to radicals in a molecular beam. To demonstrate the method, we studied three prototypical systems: the diatomic radical OD, the radical van der Waals complex Ar·OD and the polyatomic vinoxy radical (CH₂CHO). In all three cases hyperfine quantum beats were observed and identified on the fluorescence decays from excited electronic states with or without an external magnetic field. The application of this method to other radical systems is discussed.