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

We report term energies and effective quantum numbers of the odd parity 3d 2D arrow right 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 (532nm) 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 plus or minus 0.02cm-1 from the much extended 3d 2D arrow right nf 2F (17 less than or equal to n less than or equal to 70) series. In addition, the oscillator strengths of the 3d 2D arrow right nf 2F (15 less than or equal to n less than or equal to 48) transitions have been determined, showing a decreasing trend with the increase in principal quantum number n.