Direct wavelength measurement of the 4p2 3P1 - 3P0 highly charged ion clock transition in Rh13+

Magnetic dipole transitions between fine-or hyperfine-structure splitting in the np(2) P-3 ground term have been proposed to develop ultraprecise atomic clocks ( https://link.aps.org/doi/10.1103/PhysRevLett. 113.233003 Yudin et al. , Phys. Rev. Lett. 113 (2014) 233003). In the present work, a spectroscopic investi-gation of fine-structure splitting of 4p(2) P-3(1) - P-3(0) in Rh13+ is performed in a compact electron beam ion trap. By means of a dedicated internal calibration method, the transition wavelength of 321.2150(14) nm (in air) is precisely determined at a few ppm level which agrees with the previous results and improves its uncertainty by more than 350 times. (C) 2022 Elsevier Ltd. All rights reserved.