Radiative lifetime measurements in TmIII with time-resolved laser spectroscopy and comparisons with HFR calculations

Natural radiative lifetimes of eight levels in Tm m were measured with the time-resolved laser-induced fluorescence (LIF) technique. Free doubly ioniz ed thulium ions were obtained in a laser-produced plasma. Three even-parity levels were excited from the ground state with one-photon excitation, usin g a laser system generating pulses of 1 ns duration. Five odd-parity levels were excited from the ground state with two-photon excitation, where a pic osecond laser system was employed. In both cases, the lifetimes were evalua ted from transient LIF signals detected with a fast-detection system. The e xperimental lifetime results were compared with Hartree-Fock calculations i ncluding relativistic corrections. Good agreement was achieved for the 4f(1 2)6p levels while larger discrepancies are noted for some 4f(12)5d levels.