Precision measurement of the 1s2s3S1 → 1s2p 3P0,1,2 transitions in heliumlike beryllium

We have applied fast-ion-beam laser spectroscopy to observe the 1s2s3S → 1s2p3P transitions in Be III with complete resolution of the fine and hyperfine structure (I = 3/2). Using intracavity cw frequency-doubling in a Ti:Sapph laser, we produced ∼50 mW at ∼372.5 nm, continuously tunable over 60 GHz. A re-designed high-temperature ion source gave ∼50 nA of 9Be2+ at 16 keV, an order of magnitude improvement over an earlier version. Although the ∼10 nA laser-induced-fluorescence signals could be observed directly despite ∼45 nA due to scattered laser light, lock-in detection was used to obtain zero average background. The absolute wavelength reference was the Aime Cotton I2 Atlas, using linear absorption of the fundamental (745 nm). Results will be compared with theory and discussed with reference to systematic discrepancies of the 3P0 level which have been observed over a wide range of Z