Precision Measurement of the Electric Dipole Intercombination Rate inC2+

Abstract
The electric dipole intercombination decay of the 2s2p P103 level in the Be-like ion C2+ has been optically observed with ions circulating in a heavy-ion storage ring. The measured transition probability of (102.94±0.14)s1, corresponding to a lifetime of (9.714±0.013) ms, is in good agreement with recent theoretical calculations. This precision measurement thus resolves the long-standing discrepancy of data from a radiofrequency ion trap experiment with theoretical predictions.