Stark quantum beats of Ar Rydberg states

Stark quantum beats between the M = 0 and |M| = 1 magnetic sublevels of Ar atom Rydberg states were observed detecting time dependent fluorescence by using synchrotron vacuum ultraviolet radiation. Complex multiple beat frequencies were observed in Stark quantum beats spectra of Ar 18d state. A diagonalization method of the Stark energy matrix and the multi-channel quantum defect theory analysis were adopted for calculation. A comparison between experimental results and the calculated ones revealed that the multiple beat frequencies were caused by the 18d and even-parity f states.