Abstract
Laser-cooled sodium atoms pushed up on a vertical trajectory by radiation pressure are observed to turn around due to gravity. The reatively long time the atoms spent freely falling in this ‘‘atomic fountain’’ allowed the ground-state hyperfine splitting to be measured with a linewidth of 2 Hz. After a 1000-s integration time, the center of the line was resolved to ±10 mHz. The absolute splitting was measured to be 1 771 626 129(2) Hz.
- Received 15 May 1989
DOI:https://doi.org/10.1103/PhysRevLett.63.612
©1989 American Physical Society
