Abstract
We report the direct frequency measurement of the visible intercombination line of strontium that is considered a possible candidate for a future optical-frequency standard. The frequency of a cavity-stabilized laser is locked to the saturated fluorescence in a thermal Sr atomic beam and is measured with an optical-frequency comb generator referenced to the SI second through a global positioning system signal. The transition is measured to be at 434 829 121 311 (10) kHz. We measure also the isotope shift to be 163 817.4 (0.2) kHz.
- Received 12 June 2003
DOI:https://doi.org/10.1103/PhysRevLett.91.243002
©2003 American Physical Society