Laser spectroscopy of trapped atomic ions.

Recent developments in laser spectroscopy of atomic ions stored in electromagnetic traps are reviewed with emphasis on techniques that appear to hold the greatest promise of attaining extremely high resolution. Among these techniques are laser cooling and the use of single, isolated ions as experimental samples. Doppler shifts and other perturbing influences can be largely eliminated. Atomic resonances with line widths of a few parts in 10(11) have been observed at frequencies ranging from the radio frequency to the ultraviolet. Experimental accuracies of one part in 10(18) appear to be attainable.