Two-step laser excitation of the highly excited even-parity states of atomic mercury

Abstract

We report term energies and quantum defects of highly excited even-parity states of mercury in the 83 876–84 140 cm-1 energy range, employing a two-step laser excitation scheme via the $6s^2 ~^1$ S0↦6s6p3P1 inter-combination transition. Two dye lasers, pumped by a common Nd:YAG laser, were frequency doubled by BBO crystals and used to record the spectra in conjunction with a thermionic diode ion detector. Our new observations include the much extended $6snd ~^3$ D2 (22 ≤n ≤52) series and a few members of the $6sns ~^3$ S1 (24 ≤n ≤30) Rydberg series. Members of the $6snd ~^3$ D2 Rydberg series with such a high n value are reported for the first time. The relative intensities of the $msnd ~^3$ D2 and $msns ~^3$ S1 transitions (m = 4, 5 and 6) of group II-B elements excited from the $msmp ~^3$ P1 inter-combination states are also discussed.