Laser Spectroscopic Studies of Radiative Lifetime and Hyperfine Structure for Group IIA and IIIA Atoms

Sammanfattning: Studies of natural radiative lifetimes and hyperfine structure have been performed for group IIA and IIIA atoms. Different laser spectroscopic techniques such as PUMOLS, time-resolved laser spectroscopy, using transient recorder, and collimated atomic-beam experiments have been used. These methods employ cw or pulsed dye laser systems. The lifetime measurements revealed several cases in barium and strontium where the lifetimes are being perturbed by doubly excited states. Some of the data have been interpreted with MQDT. Influences of induced black-body transitions have also been observed. Different lifetime values within hyperfine structure multiplets have been shown experimentally for the first time. Hyperfine structure data from measurements in Al, Ga and In, have been used as a sensitive test for MBPT calculations for relatively heavy elements. Measurements of Lande factors in Ba using quantum-beat spectroscopy and optical double resonance were performed, allowing a refinement of the MQDT analysis for the 1130 2 sequences. Some isotope shift measurements for Ba and Ga have also been performed. Key words: Laser spectroscopy, radiative lifetimes, hyperfine structure, doubly excited states, black-body transitions, singlet- triplet mixing, alkaline-earth atoms, group IIIA atoms, Lande factors, quantum beats, isotope shift, Stark shift, dye laser, delayed-coincidence, time resolved, collimated atomic-beam.