Laser spectroscopy of Be+ 7,10 in an online ion trap

Abstract

Radioactive beryllium isotope ions (Be+7 and Be+10) that are provided by a projectile fragment separator with ≈ 1 GeV beams, as well as stable isotope ions (Be+9) are stored and laser cooled in an online ion trap. Their absolute transition energies of the 2s S 1/2 2 →2p P 3/2 2 transition were measured with an accuracy of ∼ 10-8. In this way isotope shifts of beryllium ions were obtained and the differential mass polarization parameter κ=-0.28641 (70) a.u. as well as the 2s S2 →2p P2 transition energy of an infinitely heavy beryllium ion h ν ∞ =0.145524290 (42) a.u. were determined for the first time. © 2006 The American Physical Society.