Laser spectroscopy of highly charged argon at the Heidelberg electron beam ion trap

We report on two-level laser spectroscopy on the electron dipole-forbidden 1s(2)2s(2)2p P-2(3/2)-P-2(1/2) transition in boron-like Ar13+ ions stored in an electron beam ion trap. By monitoring the laser-induced fluorescence as a function of the laser frequency, the transition wavelength was determined to be 441.25575(17) nm. The accuracy achieved in this first investigation is equal to that of the best wavelength measurements in highly charged ions.