Abstract
We demonstrate laser cooling of ions in a rf quadrupole trap using an alternative optical-excitation scheme. The metastable 45 state of , to which ions decay if the resonance (cooling) transition is driven, is depleted by driving an optical transition at a wavelength of 935 nm, which is much more attractive than the 2.438 μm radiation used previously. This couples the metastable state to a fourth energy level from which the ions decay rapidly to the ground state. Fluorescence line shapes of the cooling transition indicate that small numbers of ions were cooled in this way to kinetic temperatures below 1 K.
- Received 11 March 1991
DOI:https://doi.org/10.1103/PhysRevA.44.R20
©1991 American Physical Society