Atomic mass of6Liusing a Penning-ion-trap mass spectrometer

Abstract

The atomic mass of 6 Li has been measured using a Penning-ion-trap mass spectrometer to he 6.015 122 795(16) u. The fractional measurement uncertainty of ′2.7×10 - 9 represents a 30-fold improvement over that of the accepted published value. External ion sources were used to create ions outside the cryogenic (4 K) environment of the Penning trap and an ion-transport beamline was used to deliver ions into the trap for measurement. The ion mass ratios of 6Li+:12C2+ and 6 Li + :D + 3 were measured using this apparatus and the atomic mass of neutral 6 Li was derived from these ratios. A measurement of the He + :D + 2 mass ratio with a fractional uncertainty of ′ 1. 1× 10 - 9 and differing from the accepted published value by a fractional amount -0.6×10 - 9 is also reported.