Millimeter-wave spectroscopy of Zn I in 1D2, 1F3 and 1G4 Rydberg states

We have measured the frequencies of 24 transitions between Rydberg singlet L = 2–4 levels of zinc in the frequency range 79–285 GHz. The transitions were driven from 4snf 1F3 levels that were excited by two-step laser excitation through 4s4d 1D2. Single-photon 4snf 1F3 4s(n + 2)d 1D2, 4snf 1F3 4s(n + 3)d 1D2, 4snf 1F3 4s(n + 1)g 1G4, and two-photon 4snf 1F3 4s(n + 1)f 1F3 series for principal quantum number n = 28–40 were observed. Ritz expansion coefficients in the single-channel quantum defect theory were obtained for D, F and G states by least square fitting analysis of the spectra. An estimate of the dipole polarizability of Zn+ has been obtained.