Spectroscopic investigation of the 3d 2D → nf 2F transitions in lithium

• The term energies and effective quantum numbers of the nf 2F Rydberg states of lithium
• The first ionization potential is determined as 43,487.131 ± 0.02 cm− 1.
• Oscillator strength determination of the 3d 2D → nf 2F transitions from n = 15–48

We report term energies and effective quantum numbers of the odd parity 3d 2D → nf 2F series of lithium using multi-step and multi-photon laser excitation schemes. The experiments were performed using three dye lasers simultaneously pumped by the second harmonic (532 nm) of a Q-switched Nd:YAG laser in conjunction with an atomic beam apparatus and thermionic diode ion detector. The first ionization potential of lithium has been determined as 43,487.13 ± 0.02 cm− 1 from the much extended 3d 2D → nf 2F (17 ≤ n ≤ 70) series. In addition, the oscillator strengths of the 3d 2D → nf 2F (15 ≤ n ≤ 48) transitions have been determined, showing a decreasing trend with the increase in principal quantum number n.